From ed2c9751e26d161ad81d86a8d50985cb964d30a1 Mon Sep 17 00:00:00 2001 From: Florian Merz Date: Thu, 11 Feb 2021 14:47:01 +0100 Subject: unslug fa: move --- files/fa/web/html/applying_color/index.html | 502 +++++++++++++++++ files/fa/web/html/attributes/index.html | 607 +++++++++++++++++++++ .../index.html | 127 ----- .../index.html" | 502 ----------------- 4 files changed, 1109 insertions(+), 629 deletions(-) create mode 100644 files/fa/web/html/applying_color/index.html create mode 100644 files/fa/web/html/attributes/index.html delete mode 100644 files/fa/web/html/tips_for_authoring_fast-loading_html_pages/index.html delete mode 100644 "files/fa/web/html/\330\247\331\201\330\262\331\210\330\257\331\206_\330\261\331\206\332\257/index.html" (limited to 'files/fa/web/html') diff --git a/files/fa/web/html/applying_color/index.html b/files/fa/web/html/applying_color/index.html new file mode 100644 index 0000000000..99f2d980cf --- /dev/null +++ b/files/fa/web/html/applying_color/index.html @@ -0,0 +1,502 @@ +--- +title: اضافه کردن رنگ به عناصر با استفاده از سی اس اس +slug: Web/HTML/افزودن_رنگ +translation_of: Web/HTML/Applying_color +--- +
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The use of color is a fundamental form of human expression. Children experiment with color before they even have the manual dexterity to draw. Maybe that's why color is one of the first things people often want to experiment with when learning to develop web sites. With CSS, there are lots of ways to add color to your HTML elements to create just the look you want. This article is a primer introducing each of the ways CSS color can be used in HTML.

+ +

Fortunately, adding color to your HTML is actually really easy to do, and you can add color to nearly anything.

+ +

We're going to touch on most of what you'll need to know when using color, including a {{anch("Things that can have color", "list of what you can color and what CSS properties are involved")}}, {{anch("How to describe a color", "how you describe colors")}}, and how to actually {{anch("Using color", "use colors both in stylesheets and in scripts")}}. We'll also take a look at how to {{anch("Letting the user picka color", "let the user pick a color")}}.

+ +

Then we'll wrap things up with a brief discussion of how to {{anch("Using color wisely", "use color wisely")}}: how to select appropriate colors, keeping in mind the needs of people with differing visual capabilities.

+ +

Things that can have color

+ +

At the element level, everything in HTML can have color applied to it. Instead, let's look at things in terms of the kinds of things that are drawn in the elements, such as text and borders and so forth. For each, we'll see a list of the CSS properties that apply color to them.

+ +

At a fundamental level, the {{cssxref("color")}} property defines the foreground color of an HTML element's content and the {{cssxref("background-color")}} property defines the element's background color. These can be used on just about any element.

+ +

Text

+ +

Whenever an element is rendered, these properties are used to determine the color of the text, its background, and any decorations on the text.

+ +
+
{{cssxref("color")}}
+
The color to use when drawing the text and any text decorations (such as the addition of under- or overlines, strike-through lines, and so forth.
+
{{cssxref("background-color")}}
+
The text's background color.
+
{{cssxref("text-shadow")}}
+
Configures a shadow effect to apply to text. Among the options for the shadow is the shadow's base color (which is then blurred and blended with the background based on the other parameters). See {{SectionOnPage("/en-US/docs/Learn/CSS/Styling_text/Fundamentals", "Text drop shadows")}} to learn more.
+
{{cssxref("text-decoration-color")}}
+
By default, text decorations (such as underlines, strikethroughs, etc) use the color property as their colors. However, you can override that behavior and use a different color for them with the text-decoration-color property.
+
{{cssxref("text-emphasis-color")}}
+
The color to use when drawing emphasis symbols adjacent to each character in the text. This is used primarily when drawing text for East Asian languages.
+
{{cssxref("caret-color")}}
+
The color to use when drawing the {{Glossary("caret")}} (sometimes referred to as the text input cursor) within the element. This is only useful in elements that are editable, such as {{HTMLElement("input")}} and {{HTMLElement("textarea")}} or elements whose HTML {{htmlattrxref("contenteditable")}} attribute is set.
+
+ +

Boxes

+ +

Every element is a box with some sort of content, and has a background and a border in addition to whatever contents the box may have.

+ +
+
{{anch("Borders")}}
+
See the section {{anch("Borders")}} for a list of the CSS properties you can use to set the colors of a box's borders.
+
{{cssxref("background-color")}}
+
The background color to use in areas of the element that have no foreground content.
+
{{cssxref("column-rule-color")}}
+
The color to use when drawing the line separating columns of text.
+
{{cssxref("outline-color")}}
+
The color to use when drawing an outline around the outside of the element. This outline is different from the border in that it doesn't get space set aside for it in the document (so it may overlap other content). It's generally used as a focus indicator, to show which element will receive input events.
+
+ +

Borders

+ +

Any element can have a border drawn around it. A basic element border is a line drawn around the edges of the element's content. See {{SectionOnPage("/en-US/docs/Learn/CSS/Introduction_to_CSS/Box_model", "Box properties")}} to learn about the relationship between elements and their borders, and the article Styling borders using CSS to learn more about applying styles to borders.

+ +

You can use the {{cssxref("border")}} shorthand property, which lets you configure everything about the border in one shot (including non-color features of borders, such as its width, style (solid, dashed, etc.), and so forth.

+ +
+
{{cssxref("border-color")}}
+
Specifies a single color to use for every side of the element's border.
+
{{cssxref("border-left-color")}}, {{cssxref("border-right-color")}}, {{cssxref("border-top-color")}}, and {{cssxref("border-bottom-color")}}
+
Lets you set the color of the corresponding side of the element's border.
+
{{cssxref("border-block-start-color")}} and {{cssxref("border-block-end-color")}}
+
With these, you can set the color used to draw the borders which are closest to the start and end of the block the border surrounds. In a left-to-right writing mode (such as the way English is written), the block start border is the top edge and the block end is the bottom. This differs from the inline start and end, which are the left and right edges (corresponding to where each line of text in the box begins and ends).
+
{{cssxref("border-inline-start-color")}} and {{cssxref("border-inline-end-color")}}
+
These let you color the edges of the border closest to to the beginning and the end of the start of lines of text within the box. Which side this is will vary depending on the {{cssxref("writing-mode")}}, {{cssxref("direction")}}, and {{cssxref("text-orientation")}} properties, which are typically (but not always) used to adjust text directionality based on the language being displayed. For example, if the box's text is being rendered right-to-left, then the border-inline-start-color is applied to the right side of the border.
+
+ +

Other ways to use color

+ +

CSS isn't the only web technology that supports color. There are graphics technologies that are available on the web which also support color.

+ +
+
The HTML Canvas API
+
Lets you draw 2D bitmapped graphics in a {{HTMLElement("canvas")}} element. See our Canvas tutorial to learn more.
+
SVG (Scalable Vector Graphics)
+
Lets you draw images using commands that draw specific shapes, patterns, and lines to produce an image. SVG commands are formatted as XML, and can be embedded directly into a web page or can be placed in he page using the {{HTMLElement("img")}} element, just like any other type of image.
+
WebGL
+
The Web Graphics Library is an OpenGL ES-based API for drawing high-performance 2D and 3D graphics on the Web. See Learn WebGL for 2D and 3D graphics to find out more.
+
+ +

How to describe a color

+ +

In order to represent a color in CSS, you have to find a way to translate the analog concept of "color" into a digital form that a computer can use. This is typically done by breaking down the color into components, such as how much of each of a set of primary colors to mix together, or how bright to make the color. As such, there are several ways you can describe color in CSS.

+ +

For more detailed discussion of each of the color value types, see the reference for the CSS {{cssxref("<color>")}} unit.

+ +

Keywords

+ +

A set of standard color names have been defined, letting you use these keywords instead of numeric representations of colors if you choose to do so and there's a keyword representing the exact color you want to use. Color keywords include the standard primary and secondary colors (such as red, blue, or orange), shades of gray (from black to white, including colors like darkgray and lightgrey), and a variety of other blended colors including lightseagreen, cornflowerblue, and rebeccapurple.

+ +

See {{SectionOnPage("/en-US/docs/Web/CSS/color_value", "Color keywords", "code")}} for a list of all available color keywords.

+ +

RGB values

+ +

There are three ways to represent an RGB color in CSS.

+ +

Hexadecimal string notation

+ +

Hexadecimal string notation represents a color using hexadecimal digits to represent each of the color components (red, green, and blue). It may also include a fourth component: the alpha channel (or opacity). Each color component can be represented as a number between 0 and 255 (0x00 and 0xFF) or, optionally, as a number between 0 and 15 (0x0 and 0xF). All components must be specified using the same number of digits. If you use the single-digit notation, the final color is computed by using each component's digit twice; that is, "#D" becomes "#DD" when drawing.

+ +

A color in hexadecimal string notation always begins with the character "#". After that come the hexadecimal digits of the color code. The string is case-insensitive.

+ +
+
"#rrggbb"
+
Specifies a fully-opaque color whose red component is the hexadecimal number 0xrr, green component is 0xgg, and blue component is 0xbb.
+
"#rrggbbaa"
+
Specifies a color whose red component is the hexadecimal number 0xrr, green component is 0xgg, and blue component is 0xbb. The alpha channel is specified by 0xaa; the lower this value is, the more translucent the color becomes.
+
"#rgb"
+
Specifies a color whose red component is the hexadecimal number 0xrr, green component is 0xgg, and blue component is 0xbb.
+
"#rgba"
+
Specifies a color whose red component is the hexadecimal number 0xrr, green component is 0xgg, and blue component is 0xbb. The alpha channel is specified by 0xaa; the lower this value is, the more translucent the color becomes.
+
+ +

As an example, you can represent the opaque color bright blue as "#0000ff" or "#00f". To make it 25% opaque, you can use "#0000ff44" or "#00f4".

+ +

RGB functional notation

+ +

RGB (Red/Green/Blue) functional notation, like hexadecimal string notation, represents colors using their red, green, and blue components (as well as, optionally, an alpha channel component for opacity). However, instead of using a string, the color is defined using the CSS function {{cssxref("color_value", "rgb()", "#rgb()")}}. This function accepts as its input parameters the values of the red, green, and blue components and an optional fourth parameter, the value for the alpha channel.

+ +

Legal values for each of these parameters are:

+ +
+
red, green, and blue
+
Each must be an {{cssxref("<integer>")}} value between 0 and 255 (inclusive), or a {{cssxref("<percentage>")}} from 0% to 100%.
+
alpha
+
The alpha channel is a number between 0.0 (fully transparent) and 1.0 (fully opaque). You can also specify a percentage where 0% is the same as 0.0 and 100% is the same as 1.0.
+
+ +

For example, a bright red that's 50% opaque can be represented as rgb(255, 0, 0, 0.5) or rgb(100%, 0, 0, 50%).

+ +

HSL functional notation

+ +

Designers and artists often prefer to work using the {{interwiki("wikipedia", "HSL and HSV", "HSL")}} (Hue/Saturation/Luminosity) color method. On the web, HSL colors are represented using HSL functional notation. The hsl() CSS function is very similar to the rgb() function in usage otherwise.

+ +
+
HSL color cylinder +
Figure 1. An HSL color cylinder. Hue defines the actual color based on the position along a circular color wheel representing the colors of the visible spectrum. Saturation is a percentage of how much of the way between being a shade of gray and having the maximum possible amount of the given hue. As the value of luminance (or lightness) increases, the color transitions from the darkest possible to the brightest possible (from black to white). Image courtesy of user SharkD on Wikipedia, distributed under the CC BY-SA 3.0 license.
+
+
+ +

The value of the hue (H) component of an HSL color is an angle from red around through yellow, green, cyan, blue, and magenta (ending up back at red again at 360°) that identifies what the base color is. The value can be specified in any {{cssxref("<angle>")}} unit supported by CSS, including degrees (deg), radians (rad), gradians (grad), or turns (turn). But this doesn't control how vivid or dull, or how bright or dark the color is.

+ +

The saturation (S) component of the color specifies what percentage of the final color is comprised of the specified hue. The rest is defined by the grey level provided by the luminance (L) component.

+ +

Think of it like creating the perfect paint color:

+ +
    +
  1. You start with base paint that's the maximum intensity possible for a given color, such as  the most intense blue that can be represented by the user's screen. This is the hue (H) component: a value representing the angle around the color wheel for the vivid hue we want to use as our base.
    2. +
  2. Then select a greyscale paint that corresponds how bright you want the color to be; this is the luminance. Do you want it to be very bright and nearly white, or very dark and closer to black, or somewhere in between? This is specified using a percentage, where 0% is perfectly black and 100% is perfectly white. (regardless of the saturation or hue). In between values are a literal grey area.
    3. +
  3. Now that you have a grey paint and a perfectly vivid color, you need to mix them together. The saturation (S) component of the color indicates what percentage of the final color should be comprised of that perfectly vivid color. The rest of the final color is made up of the grey paint that represents the saturation.
    4. +
+ +

You can also optionally include an alpha channel, to make the color less than 100% opaque.

+ +

Here are some sample colors in HSL notation:

+ +
+ + +

{{EmbedLiveSample("hsl-swatches", 300, 260)}}

+
+ +
+

Note that when you omit the hue's unit, it's assumed to be in degrees (deg).

+
+ +

Using color

+ +

Now that you know what CSS properties exist that let you apply color to elements and the formats you can use to describe colors, you can put this together to begin to make use of color. As you may have seen from the list under {{anch("Things that can have color")}}, there are plenty of things you can color with CSS. Let's look at this from two sides: using color within a {{Glossary("stylesheet")}}, and adding and changing color using {{Glossary("JavaScript")}} code to alter the styles of elements.

+ +

Specifying colors in stylesheets

+ +

The easiest way to apply color to elements—and the way you'll usually do it—is to simply specify colors in the CSS that's used when rendering elements. While we won't use every single property mentioned previously, we'll look at a couple of examples. The concept is the same anywhere you use color.

+ +

Let's take a look at an example, starting by looking at the results we're trying to achieve:

+ +
{{EmbedLiveSample("Specifying_colors_in_stylesheets", 650, 150)}}
+ +

HTML

+ +

The HTML responsible for creating the above example is shown here:

+ +
<div class="wrapper">
+  <div class="box boxLeft">
+    <p>
+      This is the first box.
+    </p>
+  </div>
+  <div class="box boxRight">
+    <p>
+      This is the second box.
+    </p>
+  </div>
+</div>
+ +

This is pretty simple, using a {{HTMLElement("div")}} as a wrapper around the contents, which consists of two more <div>s, each styled differently with a single paragraph ({{HTMLElement("p")}}) in each box.

+ +

The magic happens, as usual, in the CSS, where we'll apply colors define the layout for the HTML above.

+ +

CSS

+ +

We'll look at the CSS to create the above results a piece at a time, so we can review the interesting parts one by one.

+ +
.wrapper {
+  width: 620px;
+  height: 110px;
+  margin: 0;
+  padding: 10px;
+  border: 6px solid mediumturquoise;
+}
+ +

The .wrapper class is used to assign styles to the {{HTMLElement("div")}} that encloses all of our other content. This establishes thesize of the container using {{cssxref("width")}} and {{cssxref("height")}} as well as its {{cssxref("margin")}} and {{cssxref("padding")}}.

+ +

Of more interest to our discussion here is the use of the {{cssxref("border")}} property to establish a border around the outside edge of the element. This border is a solid line, 6 pixels wide, in the color mediumturquoise.

+ +

Our two colored boxes share a number of properties in common, so next we establish a class, .box, that defines those shared properties:

+ +
.box {
+  width: 290px;
+  height: 100px;
+  margin: 0;
+  padding: 4px 6px;
+  font: 28px "Marker Felt", "Zapfino", cursive;
+  display: flex;
+  justify-content: center;
+  align-items: center;
+}
+ +

In brief, .box establishes the size of each box, as well as the configuration of the font used within. We also take advantage of CSS Flexbox to easily center the contents of each box. We enable flex mode using {{cssxref("display", "display: flex")}}, and set both {{cssxref("justify-content")}} and {{cssxref("align-items")}} to center. Then we can create a class for each of the two boxes that defines the propeties that differ between the two.

+ +
.boxLeft {
+  float: left;
+  background-color: rgb(245, 130, 130);
+  outline: 2px solid darkred;
+}
+ +

The .boxLeft class—which, cleverly, is used to style the box on the left—floats the box to the left, then sets up the colors:

+ + + +
.boxRight {
+  float: right;
+  background-color: hsl(270deg, 50%, 75%);
+  outline: 4px dashed rgb(110, 20, 120);
+  color: hsl(0deg, 100%, 100%);
+  text-decoration: underline wavy #88ff88;
+  text-shadow: 2px 2px 3px black;
+}
+ +

Finally, the .boxRight class describes the unique properties of the box that's drawn on the right. It's configured to float the box to the right so that it appears next to the previous box. Then the following colors are established:

+ + + +

Letting the user pick a color

+ +

There are many situations in which your web site may need to let the user select a color. Perhaps you have a customizable user interface, or you're implementing a drawing app. Maybe you have editable text and need to let the user choose the text color. Or perhaps your app lets the user assign colors to folders or items. Although historically it's been necessary to implement your own {{interwiki("wikipedia", "color picker")}}, HTML now provides support for browsers to provide one for your use through the {{HTMLElement("input")}} element, by using "color" as the value of its {{htmlattrxref("type", "input")}} attribute.

+ +

The <input> element represents a color only in the {{anch("Hexadecimal string notation", "hexadecimal string notation")}} covered above.

+ +

Example: Picking a color

+ +

Let's look at a simple example, in which the user can choose a color. As the user adjusts the color, the border around the example changes to reflect the new color. After finishing up and picking the final color, the color picker's value is displayed.

+ +

{{EmbedLiveSample("Example_Picking_a_color", 525, 275)}}

+ +
+

On macOS, you indicate that you've finalized selection of the color by closing the color picker window.

+
+ +

HTML

+ +

The HTML here creates a box that contains a color picker control (with a label created using the {{HTMLElement("label")}} element) and an empty paragraph element ({{HTMLElement("p")}}) into which we'll output some text from our JavaScript code.

+ +
<div id="box">
+  <label for="colorPicker">Border color:</label>
+  <input type="color" value="#8888ff" id="colorPicker">
+  <p id="output"></p>
+</div>
+ +

CSS

+ +

The CSS simply establishes a size for the box and some basic styling for appearances. The border is also established with a 2-pixel width and a border color that won't last, courtesy of the JavaScript below...

+ +
#box {
+  width: 500px;
+  height: 200px;
+  border: 2px solid rgb(245, 220, 225);
+  padding: 4px 6px;
+  font: 16px "Lucida Grande", "Helvetica", "Arial", "sans-serif"
+}
+ +

JavaScript

+ +

The script here handles the task of updating the starting color of the border to match the color picker's value. Then two event handlers are added to deal with input from the <input type="color"> element.

+ +
let colorPicker = document.getElementById("colorPicker");
+let box = document.getElementById("box");
+let output = document.getElementById("output");
+
+box.style.borderColor = colorPicker.value;
+
+colorPicker.addEventListener("input", function(event) {
+  box.style.borderColor = event.target.value;
+}, false);
+
+colorPicker.addEventListener("change", function(event) {
+  output.innerText = "Color set to " + colorPicker.value + ".";
+}, false);
+ +

The {{event("input")}} event is sent every time the value of the element changes; that is, every time the user adjusts the color in the color picker. Each time this event arrives, we set the box's border color to match the color picker's current value.

+ +

The {{event("change")}} event is received when the color picker's value is finalized. We respond by setting the contents of the <p> element with the ID "output" to a string describing the finally selected color.

+ +

Using color wisely

+ +

Making the right choices when selecting colors when designing a web site can be a tricky process, especially if you aren't well-grounded in art, design, or at least basic color theory. The wrong color choice can render your site unattractive, or even worse, leave the content unreadable due to problems with contrast or conflicting colors. Worse still, if using the wrong colors can result in your content being outright unusable by people withcertain vision problems, particularly color blindness.

+ +

Finding the right colors

+ +

Coming up with just the right colors can be tricky, especially without training in art or design. Fortunately, there are tools available that can help you. While they can't replace having a good designer helping you make these decisions, they can definitely get you started.

+ +

Base color

+ +

The first step is to choose your base color. This is the color that in some way defines your web site or the subject matter of the site. Just as we associate green with the beverage {{interwiki("wikipedia", "Mountain Dew")}} and one might think of the color blue in relationship with the sky or the ocean, choosing an appropriate base color to represent your site is a good place to start. There are plenty of ways to select a base color; a few ideas include:

+ + + +

When trying to decide upon a base color, you may find that browser extensions that let you select colors from web content can be particularly handy. Some of these are even specifically designed to help with this sort of work. For example, the web site ColorZilla offers an extension (Chrome / Firefox) that offers an eyedropper tool for picking colors from the web. It can also take averages of the colors of pixels in various sized areas or even a selected area of the page.

+ +
+

The advantage to averaging colors can be that often what looks like a solid color is actually a surprisingly varied number of related colors all used in concert, blending to create a desired effect. Picking just one of these pixels can result in getting a color that on its own looks very out of place.

+
+ +

Fleshing out the palette

+ +

Once you have decided on your base color, there are plenty of online tools that can help you build out a palette of appropriate colors to use along with your base color by applying color theory to your base color to determine appropriate added colors. Many of these tools also support viewing the colors filtered so you can see what they would look like to people with various forms of color blindness. See {{anch("Color and accessibility")}} for a brief explanation of why this matters.

+ +

A few examples (all free to use as of the time this list was last revised):

+ + + +

When designing your palette, be sure to keep in mind that in addition to the colors these tools typically generate, you'll probably also need to add some core neutral colors such as white (or nearly white), black (or nearly black), and some number of shades of gray.

+ +
+

Usually, you are far better off using the smallest number of colors possible. By using color to accentuate rather than adding color to everything on the page, you keep your content easy to read and the colors you do use have far more impact.

+
+ +

Color theory resources

+ +

A full review of color theory is beyond the scope of this article, but there are plenty of articles about color theory available, as well as courses you can find at nearby schools and universities. A couple of useful resources about color theory:

+ +
+
Color Science (Khan Academy in association with Pixar)
+
An online course which introduces concepts such as what color is, how it's percieved, and how to use colors to express ideas. Presented by Pixar artists and designers.
+
{{interwiki("wikipedia", "Color theory")}} on Wikipedia
+
Wikipedia's entry on color theory, which has a lot of great information from a technical perspective. It's not really a resource for helping you with the color sleection process, but is still full of useful information.
+
+ +

Color and accessibility

+ +

There are several ways color can be an {{Glossary("accessibility")}} problem. Improper or careless use of color can result in a web site or app that a percentage of your target audience may not be able to use adequately, resulting in lost traffic, lost business, and possibly even a public relations problem. So it's important to consider your use of color carefully.

+ +

You should do at least basic research into {{interwiki("wikipedia", "color blindness")}}. There are several kinds; the most common is red-green color blindness, which causes people to be unable to differentiate between the colors red and green. There are others, too, ranging from inabilities to tell the difference between certain colors to total inability to see color at all.

+ +
+

The most important rule: never use color as the only way to know something. If, for example, you indicate success or failure of an operation by changing the color of a shape from white to green for success and red for failure, users with red-green color-blindness won't be able to use your site properly. Instead, perhaps use both text and color together, so that everyone can understand what's happening.

+
+ +

For more information about color blindness, see the following articles:

+ + + +

Palette design example

+ +

Let's consider a quick example of selecting an appropriate color palette for a site. Imagine that you're building a web site for a new game that takes place on the planet Mars. So let's do a Google search for photos of Mars. Lots of good examples of Martian coloration there. We carefully avoid the mockups and the photos from movies. And we decide to use a photo taken by one of the Mars landers humanity has parked on the surface over the last few decades, since the game takes place on the planet's surface. We use a color picker tool to select a sample of the color we choose.

+ +

Using an eyedropper tool, we identify a color we like and determine that the color in question is #D79C7A, which is an appropriate rusty orange-red color that's so stereotypical of the Martian surface.

+ +

Having selected our base color, we need to build out our palette. We decide to use Paletton to come up with the other colors we need. Upon opening Paletton, we see:

+ +

Right after loading Paletton.

+ +

Next, we enter our color's hex code (D79C7A) into the "Base RGB" box at the bottom-left corner of the tool:

+ +

After entering base color

+ +

We now see a monochromatic palette based on the color we picked from the Mars photo. If you need a lot of related colors for some reason, those are likely to be good ones. But what we really want is an accent color. Something that will pop along side the base color. To find that, we click the "add complementary" toggle underneath the menu that lets you select the palette type (currently "Monochromatic"). Paletton computes an appropriate accent color; clicking on the accent color down in the bottom-right corner tells us that this color is #508D7C.

+ +

Now with complementary colors included.

+ +

If you're unhappy with the color that's proposed to you, you can change the color scheme, to see if you find something you like better. For example, if we don't like the proposed greenish-blue color, we can click the Triad color scheme icon, which presents us with the following:

+ +

Triad color scheme selected

+ +

That greyish blue in the top-right looks pretty good. Clicking on it, we find that it's #556E8D. That would be used as the accent color, to be used sparingly to make things stand out, such as in headlines or in the highlighting of tabs or other indicators on the site:

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Triad color scheme selected

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Now we have our base color and our accent. On top of that, we have a few complementary shades of each, just in case we need them for gradients and the like. The colors can then be exported in a number of formats so you can make use of them.

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Once you have these colors, you will probably still need to select appropriate neutral colors. Common design practice is to try to find the sweet spot where there's just enough contrast that the text is crisp and readable but not enough contrast to become harsh for the eyes. It's easy to go too far in one way or another so be sure to get feedback on your colors once you've selected them and have examples of them in use available. If the contrast is too low, your text will tend to be washed out by the background, leaving it unreadable, but if your contrast is too high, the user may find your site garish and unpleasant to look at.

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Color, backgrounds, contrast, and printing

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What looks good on screen may look very different on paper. In addition, ink can be expensive, and if a user is printing your page, they don't necessarily need all the backgrounds and such using up their precious ink when all that matters is the text itself. Most browsers, by default, remove background images when printing documents.

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If your background colors and images have been selected carefully and/or are crucial to the usefulness of the content, you can use the CSS {{cssxref("color-adjust")}} property to tell the browser that it should not make adjustments to the appearance of content.

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The default value of color-adjust, economy, indicates that the browser is allowed to make appearance changes as it deems necessary in order to try to optimize the legibility and/or print economy of the content, given the type of output device the document is being drawn onto.

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You can set color-adjust to exact to tell the browser that the element or elements on which you use it have been designed specifically to best work with the colors and images left as they are. With this set, the browser won't tamper with the appearance of the element, and will draw it as indicated by your CSS.

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Note: There is no guarantee, though, that color-adjust: exact will result in your CSS being used exactly as given. If the browser provides user preferences to change the output (such as a "don't print backgrounds" checkbox in a print dialog box), that overrides the value of color-adjust.

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See also

+ + diff --git a/files/fa/web/html/attributes/index.html b/files/fa/web/html/attributes/index.html new file mode 100644 index 0000000000..70c73bc06b --- /dev/null +++ b/files/fa/web/html/attributes/index.html @@ -0,0 +1,607 @@ +--- +title: مرجع صفت‌های HTML +slug: HTML/Attributes +translation_of: Web/HTML/Attributes +--- +

عنصرها در HTM صفت‌هایی دارند؛ این‌ها مقادیر اضافه‌ای هستند که عنصرها را پیکربندی می‌کنند یا رفتار آنها را در راه‌های گسترده‌ای به‌صورت مناسب با شرایطی که کاربران می‌خواهند تطبیق میدهند.

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نام صفتعنصرهاتوضیح
accept{{ HTMLElement("form") }}, {{ HTMLElement("input") }}فهرست انواعی که سرور قبول می‌کند، معمولا از نوع فایل.
accept-charset{{ HTMLElement("form") }}فهرستی از مجموعه کاراکترهای پشتیبانی شده.
accesskeyGlobal attributeتعیین کلید میانبری از صفحه‌کلید جهت فعال‌سازی یا افزودن focus به عنصر مورد نظر.
action{{ HTMLElement("form") }}نشانی فایلی که قرار است اطلاعات ارسالی از فرم را پردازش کند.
align{{ HTMLElement("applet") }}, {{ HTMLElement("caption") }}, {{ HTMLElement("col") }}, {{ HTMLElement("colgroup") }},  {{ HTMLElement("hr") }}, {{ HTMLElement("iframe") }}, {{ HTMLElement("img") }}, {{ HTMLElement("table") }}, {{ HTMLElement("tbody") }},  {{ HTMLElement("td") }},  {{ HTMLElement("tfoot") }} , {{ HTMLElement("th") }}, {{ HTMLElement("thead") }}, {{ HTMLElement("tr") }}تنظیمات مربوط به چینش عنصر را تعیین می‌کند.
alt +

{{ HTMLElement("applet") }}, {{ HTMLElement("area") }}, {{ HTMLElement("img") }}, {{ HTMLElement("input") }}

+ 		متن جایگزین تصویر، زمانی که تصویر قابل نمایش نباشد.
async{{ HTMLElement("script") }}نشان‌دهنده‌ی این است که اسکریپت باید به صورت نامتقارن اجرا شود.
autocomplete{{ HTMLElement("form") }}, {{ HTMLElement("input") }}نشان‌دهنده‌ی این است که آیا کنترل‌های موجود در این فرم قابلیت اختیار مقادیر پیش‌فرض مرورگر را دارند یا خیر.
autofocus{{ HTMLElement("button") }}, {{ HTMLElement("input") }}, {{ HTMLElement("keygen") }}, {{ HTMLElement("select") }}, {{ HTMLElement("textarea") }}بعد از بارگذاری صفحه، عنصر مورد نظر focus را به خود می‌گیرد.
autoplay{{ HTMLElement("audio") }}, {{ HTMLElement("video") }}پخش صوت یا تصویر به محض آماده شدن.
bgcolor{{ HTMLElement("body") }}, {{ HTMLElement("col") }}, {{ HTMLElement("colgroup") }}, {{ HTMLElement("marquee") }}, {{ HTMLElement("table") }}, {{ HTMLElement("tbody") }}, {{ HTMLElement("tfoot") }}, {{ HTMLElement("td") }}, {{ HTMLElement("th") }}, {{ HTMLElement("tr") }} +

رنگ پیش‌زمینه‌ی عنصر.

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یادداشت: این یک صفت قدیمی است که باید از ویژگی {{ Cssxref("background-color") }} در CSS به جای آن استفاده کرد.

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border{{ HTMLElement("img") }}, {{ HTMLElement("object") }}, {{ HTMLElement("table") }} +

نشان‌دهنده‌ی حاشیه‌ی عنصر مورد نظر.

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یادداشت: این یک صفت قدیمی است که باید از ویژگی {{ Cssxref("border") }} در CSS به جای آن استفاده کرد.

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buffered{{ HTMLElement("audio") }}, {{ HTMLElement("video") }}شامل بازه‌ی زمانی است که محتوای مورد نظر در آن بازه بافر شده است.
challenge{{ HTMLElement("keygen") }}رشته‌ای از حروف که به همراه کلید عمومی ارسال می‌شود.
charset{{ HTMLElement("meta") }}, {{ HTMLElement("script") }}نوع کدگذاری کاراکترهای موجود در صفحه یا اسکریپت را تعیین می‌کند.
checked{{ HTMLElement("command") }}, {{ HTMLElement("input") }}نشان‌دهنده‌ی این است که آیا عنصر مورد نظر در زمان بارگذاری صفحه باید انتخاب شود یا خیر.
cite{{ HTMLElement("blockquote") }}, {{ HTMLElement("del") }}, {{ HTMLElement("ins") }}, {{ HTMLElement("q") }}به نشانی منبع نقل قول اشاره می‌کند.
classGlobal attributeاغلب به همراه CSS به کار می‌رود تا عنصرهایی با ویژگی‌های مشترک را سبک‌دهی کند.
code{{ HTMLElement("applet") }}نشانی فایل با پیشوند class که اپلت برای بارگذاری و اجراشدن به آن نیاز دارد را، شامل می‌شود.
codebase{{ HTMLElement("applet") }}این صفت نشانی مطلق یا نسبی دایرکتوری که فایل‌های با پیشوند class مورد نیاز اپلت هستند، را شامل می‌شود.
color{{ HTMLElement("basefont") }}, {{ HTMLElement("font") }}, {{ HTMLElement("hr") }} +

این صفت رنگ متن را با توجه به دو الگوی "نام رنگ" یا "مقدار هگزادسیمال رنگ" مشخص می‌کند.

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یادداشت: این یک صفت قدیمی است که باید از ویژگی {{ Cssxref("color") }} در CSS به جای آن استفاده کرد.

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cols{{ HTMLElement("textarea") }}تعداد ستون‌های ناحیه‌ی متنی را مشخص می‌کند.
colspan{{ HTMLElement("td") }}, {{ HTMLElement("th") }}تعداد ستون‌های یک سلول (خانه) از جدول را مشخص می‌کند.
content{{ HTMLElement("meta") }}مقداری که منطبق با http-equiv یا name است.
contenteditableGlobal attributeنشان‌دهنده‌ی این است که آیا محتوای عنصر قابل ویرایش هستنند یا خیر.
contextmenuGlobal attributeID یک {{ HTMLElement("menu") }} را به عنوان منو تعیین می‌کند.
controls{{ HTMLElement("audio") }}, {{ HTMLElement("video") }}نشان‌دهنده‌ی این است که آیا مرورگر دکمه‌های کنترل فایل صوتی یا تصویری را باید نشان بدهد یا خیر.
coords{{ HTMLElement("area") }}مجموعه‌ای از مقادیر که نشان‌دهنده‌ی مختصات ناحیه‌ی مورد نظر هستند.
data{{ HTMLElement("object") }}نشانی منبع مورد نیاز را تعیین می‌کند.
datetime{{ HTMLElement("del") }}, {{ HTMLElement("ins") }}, {{ HTMLElement("time") }}نشان‌دهنده‌ی تاریخ و زمان به کار رفته در عنصر مورد نظر است.
default{{ HTMLElement("track") }}نشان‌دهنده‌ی این است که track قبل از اینکه تنظیمات کاربر تغییر کند، باید فعال شود.
defer{{ HTMLElement("script") }}نشان‌دهنده‌ی این است که اسکریپت بلافاصله بعد از بارگذاری و تفسیر صفحه باید اجرا شود.
dirGlobal attributeجهت نوشته‌شدن متن را مشخص می‌کند. مقادیر قابل قبول عبارتند از ltr (چپ به راست)و rtl (راست به چپ)
dirname{{ HTMLElement("input") }}, {{ HTMLElement("textarea") }} 
disabled{{ HTMLElement("button") }}, {{ HTMLElement("command") }}, {{ HTMLElement("fieldset") }}, {{ HTMLElement("input") }}, {{ HTMLElement("keygen") }}, {{ HTMLElement("optgroup") }}, {{ HTMLElement("option") }}, {{ HTMLElement("select") }}, {{ HTMLElement("textarea") }}نشان‌دهنده‌ی این است که آیا کاربر امکان تعامل با عنصر مورد نظر را دارد یا خیر.
draggableGlobal attributeقابلیت کشیده‌شدن عنصر (کلیک بر روی آن و حرکت دادنش) را تعیین می‌کند.
dropzoneGlobal attributeناحیه‌ای که عنصر کشیده‌شده را می‌توان در آن رها (drop) کرد.
enctype{{ HTMLElement("form") }}وقتی از method ای مانند POST برای ارسال مقادیر فرم استفاده می‌شود، این صفت نوع محتوای داده‌ای را در فرم تعیین می‌کند.
for{{ HTMLElement("label") }}, {{ HTMLElement("output") }}تعیین عنصرهایی که به عنصر مورد نظر تعلق دارند.
form{{ HTMLElement("button") }}, {{ HTMLElement("fieldset") }}, {{ HTMLElement("input") }}, {{ HTMLElement("keygen") }}, {{ HTMLElement("label") }}, {{ HTMLElement("meter") }}, {{ HTMLElement("object") }}, {{ HTMLElement("output") }}, {{ HTMLElement("progress") }}, {{ HTMLElement("select") }}, {{ HTMLElement("textarea") }}نشان‌دهنده‌ی فرمی است که مالک (پدر) عنصر مورد نظر است.
headers{{ HTMLElement("td") }}, {{ HTMLElement("th") }}IDهای عنصر(های) <th> که به این عنصر مربوط می‌شوند.
height{{ HTMLElement("canvas") }}, {{ HTMLElement("embed") }}, {{ HTMLElement("iframe") }}, {{ HTMLElement("img") }}, {{ HTMLElement("input") }}, {{ HTMLElement("object") }}, {{ HTMLElement("video") }} +

در برخی کاربردها مانند {{ HTMLElement("div") }}، این یک صفت قدیمی است که باید از ویژگی {{ Cssxref("height") }} در CSS به جای آن استفاده کرد. در سایر موارد مانند {{ HTMLElement("canvas") }} استفاده از این صفت ضروری است.

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hiddenGlobal attributeارتباط یک عنصر را نشان می‌دهد.
high{{ HTMLElement("meter") }}پایین‌ترین مرز از بالاترین محدوده را نشان می‌دهد.
href{{ HTMLElement("a") }}, {{ HTMLElement("area") }}, {{ HTMLElement("base") }}, {{ HTMLElement("link") }}نشانی منبعی که پیوند (لینک) به آن اشاره دارد.
hreflang{{ HTMLElement("a") }}, {{ HTMLElement("area") }}, {{ HTMLElement("link") }}زبان منبعی که پیوند (لینک) به آن اشاره دارد.
http-equiv{{ HTMLElement("meta") }} 
icon{{ HTMLElement("command") }}تصویری که نشان‌دهنده‌ی command باشد را تعیین می‌کند.
idGlobal attributeاغلب با CSS به کار می‌رود تا عنصر مورد نظر را سبک دهی کند. مقدار این صفت باید منحصر به فرد (یکتا) باشد.
ismap{{ HTMLElement("img") }}نشان‌دهنده‌ی این است که آیا تصویر بخشی از یک image map سمت سرور می‌باشد یا خیر.
itempropGlobal attribute 
keytype{{ HTMLElement("keygen") }}نوع کلید تولید شده را مشخص می‌کند.
kind{{ HTMLElement("track") }}گونه‌ی متنی track را مشخص می‌کند.
label{{ HTMLElement("track") }}متنی خوانا برای track مشخص می‌کند.
langGlobal attributeزبانی که در عنصر مورد نظر به کار رفته است را مشخص می‌کند.
language{{ HTMLElement("script") }}زبان اسکریپت را در عنصر مورد نظر تعیین می‌کند.
list{{ HTMLElement("input") }}فهرستی از گزینه‌های از پیش تعریف شده را برای کاربر مشخص می‌کند.
loop{{ HTMLElement("audio") }}, {{ HTMLElement("bgsound") }}, {{ HTMLElement("marquee") }}, {{ HTMLElement("video") }}نشان‌دهنده‌ی این است که آیا محتوای مورد نظر (متن، صوت یا تصویر) پس از تمام شدن، دوباره باید اجرا شود یا به نمایش دربیاید یا خیر.
low{{ HTMLElement("meter") }}بالاترین مرز از پایین‌ترین محدوده را نشان می‌دهد.
manifest{{ HTMLElement("html") }}نشانی فایل cache manifest (جهت مرور آفلاین صفحات) را در سند مشخص می‌کند.
max{{ HTMLElement("input") }}, {{ HTMLElement("meter") }}, {{ HTMLElement("progress") }}نشان‌دهنده‌ی بیشترین مقدار مجاز است.
maxlength{{ HTMLElement("input") }}, {{ HTMLElement("textarea") }}بیشترین تعداد کاراکترها را در عنصر مورد نظر تعیین می‌کند.
media{{ HTMLElement("a") }}, {{ HTMLElement("area") }}, {{ HTMLElement("link") }}, {{ HTMLElement("source") }}, {{ HTMLElement("style") }}بخش کوچکی از رسانه که منبع پیوند داده شده برای آن طراحی شده است، را مشخص می‌کند.
method{{ HTMLElement("form") }}مشخص می‌کند که از کدام متد HTTP برای ارسال داده‌های فرم استفاده شود، که می‌تواند GET (پیش‌فرض) یا POST باشد.
min{{ HTMLElement("input") }}, {{ HTMLElement("meter") }}نشان‌دهنده‌ی کمترین مقدار مجاز است.
multiple{{ HTMLElement("input") }}, {{ HTMLElement("select") }} +

نشان‌دهنده‌ی این است که آیا مقدارهای چندتایی می‌توانند در ورودی‌های email یا file وارد شوند یا خیر.

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name{{ HTMLElement("button") }}, {{ HTMLElement("form") }}, {{ HTMLElement("fieldset") }}, {{ HTMLElement("iframe") }}, {{ HTMLElement("input") }}, {{ HTMLElement("keygen") }}, {{ HTMLElement("object") }}, {{ HTMLElement("output") }}, {{ HTMLElement("select") }}, {{ HTMLElement("textarea") }}, {{ HTMLElement("map") }}, {{ HTMLElement("meta") }}, {{ HTMLElement("param") }} +

نام عنصر. برای نمونه از این صفت برای شناسایی فیلدهای مورد نظر که به سمت سرور ارسال شده‌اند استفاده می‌شود.

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novalidate{{ HTMLElement("form") }} +

این صفت نشان‌دهنده‌ی این است که هنگام ارسال فرم، داده‌های آن نباید مورد سنجش و ارزیابی قرار بگیرند.

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open{{ HTMLElement("details") }} +

نشان‌دهنده‌ی این است که آیا جزییات زمان بارگذاری صفحه نمایش داده می‌شوند یا خیر.

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optimum{{ HTMLElement("meter") }} +

نشان‌دهنده‌ی مقدار عددی بهینه است.

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pattern{{ HTMLElement("input") }} +

عبارتی منظم را تعریف می‌کند که مقدار عنصر مورد نظر برابر آن مورد سنجش و ارزیابی قرار می‌گیرد.

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ping{{ HTMLElement("a") }}, {{ HTMLElement("area") }} 
placeholder{{ HTMLElement("input") }}, {{ HTMLElement("textarea") }} +

با نمایش کادری کوچک به کاربر اطلاع می‌دهد که چه چیزی در فیلد قابل نوشتن است.

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poster{{ HTMLElement("video") }} +

نشانی که به یک فریم از فیلم اشاره دارد تا زمانی که کاربر هنوز اقدام به پخش فیلم نکرده است به وی نمایش داده شود.

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preload{{ HTMLElement("audio") }}, {{ HTMLElement("video") }}نشان‌دهنده‌ی این است که آیا تمام منبع، بخشی از آن یا هیچ چیز باید از قبل از اقدام کاربر برای پخش محتوا، بارگذاری شود.
pubdate{{ HTMLElement("time") }} +

نشان‌دهنده‌ی این است که آیا این تاریخ و زمان مطابق با تاریخ نزدیک‌ترین عنصر {{ HTMLElement("article") }} والد خود است یا خیر.

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radiogroup{{ HTMLElement("command") }} 
readonly{{ HTMLElement("input") }}, {{ HTMLElement("textarea") }} +

نشان‌دهنده‌ی این است که آیا این عنصر قابل ویرایش است یا خیر.

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rel{{ HTMLElement("a") }}, {{ HTMLElement("area") }}, {{ HTMLElement("link") }}ارتباط بین شی هدف و شی پینوندی را مشخص می‌کند.
required{{ HTMLElement("input") }}, {{ HTMLElement("select") }}, {{ HTMLElement("textarea") }}نشان‌دهنده‌ی این است که آیا این عنصر (از فرم) نیاز به تکمیل شدن از طرف کاربر دارد یا خیر.
reversed{{ HTMLElement("ol") }}نشان‌دهنده‌ی این است که آیا فهرست باید به ترتیب نزولی نمایش داده شود، بر خلاف ترتیب صعودی.
rows{{ HTMLElement("textarea") }}تعداد سطرهای ناحیه‌ی متنی را مشخص می‌کند.
rowspan{{ HTMLElement("td") }}, {{ HTMLElement("th") }}تعداد سطرهایی که سلول (خانه) جدول باید بر اساس آن ایجاد شود را مشخص می‌‌کند.
sandbox{{ HTMLElement("iframe") }} 
spellcheckGlobal attributeنشان‌دهنده‌ی این است که آیا عملیات بررسی واژه‌ها برای این عنصر مجاز است یا خیر.
scope{{ HTMLElement("th") }} 
scoped{{ HTMLElement("style") }} 
seamless{{ HTMLElement("iframe") }} 
selected{{ HTMLElement("option") }}مقداری را تعیین می‌کند که در زمان بارگذاری صفحه، در فهرست انتخاب شده است.
shape{{ HTMLElement("a") }}, {{ HTMLElement("area") }} 
size{{ HTMLElement("input") }}, {{ HTMLElement("select") }}عرض عنصر را (بر اساس پیکسل) تعیین می‌کند. اگر عنصر مورد نظر از نوع text یا password باشد این صفت تعداد کاراکترهای عنصر را تعیین می‌کند.
sizes{{ HTMLElement("link") }} 
span{{ HTMLElement("col") }}, {{ HTMLElement("colgroup") }} 
src{{ HTMLElement("audio") }}, {{ HTMLElement("embed") }}, {{ HTMLElement("iframe") }}, {{ HTMLElement("img") }}, {{ HTMLElement("input") }}, {{ HTMLElement("script") }}, {{ HTMLElement("source") }}, {{ HTMLElement("track") }}, {{ HTMLElement("video") }}نشانی فایلی که عنصر مورد نظر از آن به عنوان منبع استفاده می‌کند.
srcdoc{{ HTMLElement("iframe") }} 
srclang{{ HTMLElement("track") }} 
start{{ HTMLElement("ol") }}اولین عدد در فهرست را تعیین می‌کند، اگر غیر از ۱ باشد.
step{{ HTMLElement("input") }} 
styleGlobal attributeسبک‌های CSS را تعریف می‌کند که در صورت وجود فایل‌های قدیمی بر روی آن‌ها نوشته می‌شوند.
summary{{ HTMLElement("table") }} 
tabindexGlobal attributeبا ویرایش این صفت، ترتیب انتخاب شدن عنصر‌های صفحه در مرورگر به حالتی که برایش تعیین شود تغییر می‌یابد.
target{{ HTMLElement("a") }}, {{ HTMLElement("area") }}, {{ HTMLElement("base") }}, {{ HTMLElement("form") }} 
titleGlobal attributeمتنی که در یک کادر کوچک با قرار دادن mouse روی عنصر مورد نظر نمایش می‌یابد.
type{{ HTMLElement("button") }}, {{ HTMLElement("input") }}, {{ HTMLElement("command") }}, {{ HTMLElement("embed") }}, {{ HTMLElement("object") }}, {{ HTMLElement("script") }}, {{ HTMLElement("source") }}, {{ HTMLElement("style") }}, {{ HTMLElement("menu") }}نوع عنصر را تعریف می‌کند.
usemap{{ HTMLElement("img") }},  {{ HTMLElement("input") }}, {{ HTMLElement("object") }} 
value{{ HTMLElement("button") }}, {{ HTMLElement("option") }}, {{ HTMLElement("input") }}, {{ HTMLElement("li") }}, {{ HTMLElement("meter") }}, {{ HTMLElement("progress") }}, {{ HTMLElement("param") }}مقدار پیش‌فرضی که در زمان بارگذاری صفحه برای عنصر انتخاب می‌شود را تعیین می‌کند.
width{{ HTMLElement("canvas") }}, {{ HTMLElement("embed") }}, {{ HTMLElement("iframe") }}, {{ HTMLElement("img") }}, {{ HTMLElement("input") }}, {{ HTMLElement("object") }}, {{ HTMLElement("video") }} +

در برخی موارد مانند {{ HTMLElement("div") }} این یک صفت قدیمی به حساب می‌آید که باید از ویژگی {{ Cssxref("width") }} در CSS به جای آن استفاده کرد. در سایر موارد مانند {{ HTMLElement("canvas") }} این یک صفت ضروری است که باید ذکر شود.

+
wrap{{ HTMLElement("textarea") }}نشان‌دهنده‌ی این است که آیا متن باید کوتاه شود یا خیر.
+

Content versus IDL attributes

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In HTML, most attributes have two faces: the content attribute and the IDL attribute.

+

The content attribute is the attribute as you set it from the content (the HTML code) and you can set it or get it via {{domxref("element.setAttribute()")}} or {{domxref("element.getAttribute()")}}. The content attribute is always a string even when the expected value should be an integer. For example, to set an {{HTMLElement("input")}} element's maxlength to 42 using the content attribute, you have to callsetAttribute("maxlength", "42") on that element.

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The IDL attribute is also known as a JavaScript property. These are the attributes you can read or set using JavaScript properties like element.foo. The IDL attribute is always going to use (but might transform) the underlying content attribute to return a value when you get it and is going to save something in the content attribute when you set it. In other words, the IDL attributes, in essence, reflect the content attributes.

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Most of the time, IDL attributes will return their valules as they are really used. For example, the default type for {{HTMLElement("input")}} elements is "text", so if you setinput.type="foobar", the <input> element will be of type text (in the appearance and the behavior) but the "type" content attribute's value will be "foobar". However, thetype IDL attribute will return the string "text".

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IDL attributes are not always strings; for example, input.maxlength is a number (a signed long). When using IDL attributes, you read or set values of the desired type, soinput.maxlength is always going to return a number and when you setinput.maxlength ,it wants a number. If you pass another type, it is automatically converted to a number as specified by the standard JavaScript rules for type conversion.

+

IDL attributes can reflect other types such as unsigned long, URLs, booleans, etc. Unfortunately, there are no clear rules and the way IDL attributes behave in conjunction with their corresponding content attributes depends on the attribute. Most of the time, it will follow the rules laid out in the specification, but sometimes it doesn't. HTML specifications try to make this as developer-friendly as possible, but for various reasons (mostly historical), some attributes  behave oddly (select.size, for example) and you should read the specifications to understand how exactly they behave.

+

See also

+ diff --git a/files/fa/web/html/tips_for_authoring_fast-loading_html_pages/index.html b/files/fa/web/html/tips_for_authoring_fast-loading_html_pages/index.html deleted file mode 100644 index 94048c4ba7..0000000000 --- a/files/fa/web/html/tips_for_authoring_fast-loading_html_pages/index.html +++ /dev/null @@ -1,127 +0,0 @@ ---- -title: نکاتی درباره‌ی ایجاد صفحات HTML سریع -slug: Web/HTML/Tips_for_authoring_fast-loading_HTML_pages -translation_of: Learn/HTML/Howto/Author_fast-loading_HTML_pages ---- -

نکات زیر بر اساس دانش و تجربه به دست آمده‌اند.

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یک صفحه‌ی وب بهینه نه تنها برای مخاطب‌های شما تعاملی‌تر است، بلکه روی وب‌سرور و اتصال اینترنت شما نیز تاثیرگذار است. این امر می‌تواند برای سایت‌هایی که ترافیک بالایی دارند مانند سایت‌های خبری، مساله‌ای اساسی باشد.

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بهینه‌سازی عملکرد یک صفحه فقط برای کاربران با اینترنت کم سرعت مطرح نیست. بلکه برای آن دسته از کاربران با اینترنت پرسرعت نیز تاثیر به سزایی دارد.

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نکته‌ها

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کاهش دادن وزن صفحه

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وزن صفحه، یکی از مهم‌ترین فاکتورهای بارگیری یک صفحه است.

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کاهش وزن صفحه به این معنا است که با حذف کردن جاهای خالی و خطوط کمکی (comment) و با انتقال اسکریپت‌ها و برگه‌های سبک سلسله‌مراتبی به فایل‌های خارجی، سرعت بارگیری صفحه را تا حد امکان افزایش دهیم.

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ابزاری مانند HTML Tidy می‌توانند به صورت خودکار جاهای خالی اضافی را از یک سند HTML حذف کنند. ابزار دیگری نیز وجود دارند که فایل‌های جاوااسکریپت را با تکنیک‌های فشرده‌سازی، فشرده کرده و با کاهش حجم آن‌ها باعث افزایش سرعت بارگیری صفحه می‌شوند.

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کاهش تعداد فایل‌ها

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با کاهش یافتن تعداد فایل‌های مورد نیاز یک صفحه، تعداد درخواست‌های HTTP جهت بارگیری صفحه نیز کاهش می‌یابد.

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بسته به تنظیمات حافظه‌ی نهان مرورگر، ممکن است درخواست If-Modified-Since به وب‌سرور برای هر فایل CSS، جاوااسکریپت یا تصویر فرستاده شود که در آن مشخص می‌شود آیا فایل نسبت به آخرین باری که دانلود شده، تغییر کرده است یا خیر.

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با کاهش تعداد فایل‌هایی که در یک صفحه به آن‌ها ارجاع داده می‌شود، تعداد درخواست‌ها به سرور و پاسخ‌هایی که از سرور ارسال می‌شود نیز کاهش می‌یابد.

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اگر از تصاویر پس‌زمینه در فایل CSS خود به نسبت زیادی استفاده می‌کنید می‌توانید با استفاده از تکینیکی به نام image sprite این تصاویر را با هم ترکیب کنید تا تعداد درخواست‌های ارسالی به سرور کاهش یابد. تنها کافی است با تغییر موقعیت تصویر در صفحه نحوه‌ی نمایش آن را در حالت‌های مختلف تنظیم کنید. این تکنیک برای عنصرهایی که ابعاد محدودی در صفحه دارند به خوبی کار می‌کند. اگرچه تعداد درخواست‌های http کمتر و cache کردن هر تصویر نیز می‌تواند به عنوان راه حل جایگزین مطرح باشد.

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زمان زیادی که صرف می‌شود تا آخرین تاریخ تغییر یک فایل مشخص شود، می‌تواند منجر به تاخیر در نمایش اولیه از یک صفحه شود، چرا که مرورگر قبل از اینکه صفحه را پردازش کند باید زمان تغییر یا modification هر فایل  CSS یا جاوااسکریپت را بررسی کند.

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کاهش تعداد ارجاع‌ها به دامنه‌های مختلف

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از آن‌جایی که هر دامنه‌ی منحصر به فرد در فرآیند DNS Lookup هزینه‌ی زمانی دارد، زمان بارگذاری صفحه با توجه به تعداد دامنه‌های مختلف در فایل‌های CSS ،جاوااسکریپت و تصویرها افزایش می‌یابد.

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با این حال همیشه به یاد داشته باشید تا آن‌جا که ممکن است از حداقل تعداد دامنه‌های مختلف در صفحات سایت استفاده کنید.

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محتوای کاربردی را Cache کنید

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اطمینان یابید هر محتوایی که قابل cache شدن است، این اتفاق برایش افتاده باشد و زمان پایانی cache نیز دارا باشد.

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در حقیقت باید به فایل سرآیند (header) با نام Last-Modified توجه خاصی داشت. کار این فایل ذخیره‌سازی آخرین زمانی است که به صفحات ثابت (html و css و ...) از طریق user agent یا همان مرورگر بر اساس زمان موجود در وب سرور، ارجاع شده است. البته این موضوع در رابطه با صفحات پویا (php و aspx و ...) اتفاق نمی‌افتد، یعنی این فایل سرآیند ارسال نمی‌شود.

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درباره‌ی صفحاتی که به صورت پویا ایجاد می‌شوند، اندکی تحقیق در این باره می‌تواند بسیار مفید باشد. با استفاده از پیوندهای زیر اطلاعات بیشتری درباره‌ی cache کردن صفحات پویا کسب کنید:

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  1. HTTP Conditional Get for RSS Hackers
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  2. HTTP 304: Not Modified
    3. -
  3. On HTTP Last-Modified and ETag
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ترتیب بهینه‌ی اجزای تشکیل دهنده‌ی صفحه

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ابتدا محتوای صفحه بارگذاری شود، همراه با هرفایل CSS یا JavaScript که در نمایش اولیه‌ی آن تاثیر دارد، تا کاربر بتواند در کوتاه‌ترین زمان ممکن به محتوای صفحه دسترسی داشته باشد. این محتوا معمولا از متن تشکیل می‌شود که در زمان کوتاهی می‌تواند در اختیار کاربر قرار گیرد.

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هرگونه ویژگی پویا که پس از بارگذاری کامل صفحه مورد نیاز هستند، در مرحله‌ی اول باید غیرفعال گردد و تنها زمانی فعال شود که تمام محتوای صفحه بارگذاری شده باشد. از جمله‌ی این ویژگی‌ها می‌توان به فایل‌های JavaScript اشاره کرد که در انتهای سند قرار می‌گیرند که این امر موجب بارگذاری سریع صفحات می‌شود.

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کاهش تعداد اسکریپت‌های برخط (inline)

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این نوع اسکریپت‌ها می‌توانند زمان زیادی را به خود اختصاص دهند، چرا که parser باید در نظر بگیرد که یک اسکریپت برخط می‌تواند ساختار صفحه را هنگامی که خود صفحه در حال parse شدن است، تغییر دهد. کاهش تعداد این اسکریپت‌ها به صورت عمومی، و کاهش استفاده از document.write به صورت اختصاصی، می‌تواند منجر به افزایش سرعت در بارگذاری صفحات شود. همچنین استفاده از روش‌های پیشرفته در AJAX جهت تغییر در محتوای صفحه به جای استفاده از document.write توصیه می‌شود.

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استفاده از CSS پیشرفته و عنصرهای معتبر

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استفاده از CSS به صورت صحیح می‌تواند تعداد عنصرهای مورد نیاز در صفحه را به شکل قابل ملاحظه‌ای کاهش دهد. از جمله این تکنیک‌ها می‌توان به جایگزین کردن برخی تصاویر (که به spacer معروف هستند) با معادل CSS آن‌ها جهت قالب‌بندی صفحه اشاره کرد.

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استفاده از عنصرهای معتبر نیز مزایای خود را دارد. اول از همه، مرورگرها دیگر نیازی ندارند تا فرآیند بررسی خطا در کد HTML را انجام دهند. ((البته این موضوع با بحث فلسفی آن که ابتدا کاربر محتوای خود را وارد می‌کند سپس به صورت منطقی فرآیند بررسی آن محتوا آغار می‌شود، متفاوت است)).

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به علاوه، استفاده از عنصرهای معتبر این امکان را در اختیار سایر ابزار می‌گذارد تا صفحات سایت شما را بررسی (pre-process) کنند. برای نمونه، HTML Tidy می‌تواند فضای خالی در صفحات و تگ‌های پایانی اختیاری را حذف کند; اگرچه این ابزار در صفحاتی که دارای خطاهای بسیار در عنصرها باشند، اجرا نمی‌شود.

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محتوا را طبقه‌بندی کنید

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استفاده از جدول‌ها در قالب‌بندی صفحات یک روش منسوخ است که دیگر نباید استفاده شود. در عوض از عنصر {{ HTMLElement("div") }} و در آینده‌ی نزدیک از ساختار چند ستونی CSS3 یا ساختار منعطف جعبه‌ای CSS3 باید استفاده شود.

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جدول‌ها هنوز هم به عنوان عنصرهای معتبر در صفحه شناخته می‌شوند اما تنها باید برای نمایش داده‌های جدولی استفاده گردند. برای این که مرورگرها صفحه‌ی شما را سریع‌تر پردازش کنند باید از جدول‌های تودرتو خودداری کنید.

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به جای این‌که از ساختاری مانند این استفاده کنید:

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<TABLE>
-  <TABLE>
-    <TABLE>
-          ...
-    </TABLE>
-  </TABLE>
-</TABLE>
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در عوض از جدول‌هایی که جداگانه هستند یا divها استفاده کنید.

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<TABLE>...</TABLE>
-<TABLE>...</TABLE>
-<TABLE>...</TABLE>
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همچنین می‌توانید مستندات CSS3 Multi-column Layout یا CSS3 Flexible Box Layout را مشاهده کنید.

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مشخص کردن اندازه‌ی تصویرها و جدول‌ها

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اگر مرورگر به محض دریافت تصویر یا جدول بتواند اندازه‌ی آن را تشخیص دهد، این امر موجب نمایش هر چه بهتر محتوای صفحه در زمان بارگذاری خواهد شد. به همین منظور استفاده از height و width برای تصویرها در هر جایی که ممکن است باید استفاده گردند.

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برای جدول‌ها نیز می‌توان از قطعه کد CSS زیر استفاده کرد:

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  table-layout: fixed;
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همچنین باید از تگ‌های COL و COLGROUP برای مشخص کردن عرض جدول‌های استفاده کرد.

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حداقل محدودیت‌های مرورگر را در نظر بگیرید

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برای این‌که صفحه‌ی شما در مرورگرهای مختلف با کمترین اختلاف ممکن نمایش داده شود، اطمینان یابید که حداقل استانداردهای مورد نیاز مرورگرها در پروژه‌هایتان رعایت شده باشند. این بدان معنا نیست که محتوای شما باید در تمامی مرورگرها دقیقا به یک شکل نمایش یابد، به خصوص مرورگرهای قدیمی.

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در حقیقت، حداقل پیش‌نیازهای شما باید منطبق با مرورگرهای پیشرفته‌ای باشند که استانداردهای وب را رعایت می‌کنند که این مرورگرها شامل Firefox 3.6 به بالا برای تمامی پلتفرم‌ها، Internet Explorer 8 به بالا در ویندوز، Opera 10 به بالا در ویندوز و Safari 4 به بالا در Mac OS X هستند.

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اگرچه، بسیاری از نکاتی که در این مقاله فهرست شده‌اند، تکنیک‌های عمومی هستند که می‌توان برای هر مرورگری و برای هر صفحه‌ی وب به کار برد، جدا از پشتیبانی مرورگرها.

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ساختار صفحه‌ی مورد نظر ما

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· HTML

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- · HEAD
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- · LINK ...
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- فایل‌های CSS که جهت نمایش صفحه مورد نیاز هستند. تعداد این فایل‌ها را پایین نگه دارید تا عملکرد صفحه افزایش یابد. همچنین می‌توان سایر فایل‌های CSS نامربتط با این صفحه را در فایل‌های دیگر قرار داد.
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- · SCRIPT ...
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- فایل‌های JavaScript که موردنیاز توابعی هستند که در زمان بارگذاری صفحه فراخوانی می‌شوند. تعداد این فایل‌ها را جهت عملکرد بهتر صفحه، پایین نگه دارید.
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- · BODY
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- محتوای مورد نظر صفحه که در قالب جدول‌ها یا divها گردآوری شده‌اند. این محتوا می‌تواند جدا از سایر اجزای صفحه نمایش یابد.
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- · SCRIPT ...
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- هر اسکریپتی که در ساختار صفحه (DHTML) تغییر ایجاد می‌کند. این اسکریپت‌ها می‌توانند پس از بارگذاری تمام صفحه و نمایش محتوا به کاربر، اجرا شوند. بنابراین دلیلی ندارد که بارگذاری آن‌ها قبل از محتوا صورت گیرد که در این صورت نمایش محتوا به کاربر با تاخیر همراه می‌شود.
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- اگر تصویری جهت حرکت‌های rollover در نظر گرفته‌اید، باید در این قسمت از صفحه preload یا پیش‌بارگذاری شوند، جایی که محتوای صفحه قبل از آن نمایش داده شده است.
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Original Document Information

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diff --git "a/files/fa/web/html/\330\247\331\201\330\262\331\210\330\257\331\206_\330\261\331\206\332\257/index.html" "b/files/fa/web/html/\330\247\331\201\330\262\331\210\330\257\331\206_\330\261\331\206\332\257/index.html" deleted file mode 100644 index 99f2d980cf..0000000000 --- "a/files/fa/web/html/\330\247\331\201\330\262\331\210\330\257\331\206_\330\261\331\206\332\257/index.html" +++ /dev/null @@ -1,502 +0,0 @@ ---- -title: اضافه کردن رنگ به عناصر با استفاده از سی اس اس -slug: Web/HTML/افزودن_رنگ -translation_of: Web/HTML/Applying_color ---- -
{{HTMLRef}}
- -

The use of color is a fundamental form of human expression. Children experiment with color before they even have the manual dexterity to draw. Maybe that's why color is one of the first things people often want to experiment with when learning to develop web sites. With CSS, there are lots of ways to add color to your HTML elements to create just the look you want. This article is a primer introducing each of the ways CSS color can be used in HTML.

- -

Fortunately, adding color to your HTML is actually really easy to do, and you can add color to nearly anything.

- -

We're going to touch on most of what you'll need to know when using color, including a {{anch("Things that can have color", "list of what you can color and what CSS properties are involved")}}, {{anch("How to describe a color", "how you describe colors")}}, and how to actually {{anch("Using color", "use colors both in stylesheets and in scripts")}}. We'll also take a look at how to {{anch("Letting the user picka color", "let the user pick a color")}}.

- -

Then we'll wrap things up with a brief discussion of how to {{anch("Using color wisely", "use color wisely")}}: how to select appropriate colors, keeping in mind the needs of people with differing visual capabilities.

- -

Things that can have color

- -

At the element level, everything in HTML can have color applied to it. Instead, let's look at things in terms of the kinds of things that are drawn in the elements, such as text and borders and so forth. For each, we'll see a list of the CSS properties that apply color to them.

- -

At a fundamental level, the {{cssxref("color")}} property defines the foreground color of an HTML element's content and the {{cssxref("background-color")}} property defines the element's background color. These can be used on just about any element.

- -

Text

- -

Whenever an element is rendered, these properties are used to determine the color of the text, its background, and any decorations on the text.

- -
-
{{cssxref("color")}}
-
The color to use when drawing the text and any text decorations (such as the addition of under- or overlines, strike-through lines, and so forth.
-
{{cssxref("background-color")}}
-
The text's background color.
-
{{cssxref("text-shadow")}}
-
Configures a shadow effect to apply to text. Among the options for the shadow is the shadow's base color (which is then blurred and blended with the background based on the other parameters). See {{SectionOnPage("/en-US/docs/Learn/CSS/Styling_text/Fundamentals", "Text drop shadows")}} to learn more.
-
{{cssxref("text-decoration-color")}}
-
By default, text decorations (such as underlines, strikethroughs, etc) use the color property as their colors. However, you can override that behavior and use a different color for them with the text-decoration-color property.
-
{{cssxref("text-emphasis-color")}}
-
The color to use when drawing emphasis symbols adjacent to each character in the text. This is used primarily when drawing text for East Asian languages.
-
{{cssxref("caret-color")}}
-
The color to use when drawing the {{Glossary("caret")}} (sometimes referred to as the text input cursor) within the element. This is only useful in elements that are editable, such as {{HTMLElement("input")}} and {{HTMLElement("textarea")}} or elements whose HTML {{htmlattrxref("contenteditable")}} attribute is set.
-
- -

Boxes

- -

Every element is a box with some sort of content, and has a background and a border in addition to whatever contents the box may have.

- -
-
{{anch("Borders")}}
-
See the section {{anch("Borders")}} for a list of the CSS properties you can use to set the colors of a box's borders.
-
{{cssxref("background-color")}}
-
The background color to use in areas of the element that have no foreground content.
-
{{cssxref("column-rule-color")}}
-
The color to use when drawing the line separating columns of text.
-
{{cssxref("outline-color")}}
-
The color to use when drawing an outline around the outside of the element. This outline is different from the border in that it doesn't get space set aside for it in the document (so it may overlap other content). It's generally used as a focus indicator, to show which element will receive input events.
-
- -

Borders

- -

Any element can have a border drawn around it. A basic element border is a line drawn around the edges of the element's content. See {{SectionOnPage("/en-US/docs/Learn/CSS/Introduction_to_CSS/Box_model", "Box properties")}} to learn about the relationship between elements and their borders, and the article Styling borders using CSS to learn more about applying styles to borders.

- -

You can use the {{cssxref("border")}} shorthand property, which lets you configure everything about the border in one shot (including non-color features of borders, such as its width, style (solid, dashed, etc.), and so forth.

- -
-
{{cssxref("border-color")}}
-
Specifies a single color to use for every side of the element's border.
-
{{cssxref("border-left-color")}}, {{cssxref("border-right-color")}}, {{cssxref("border-top-color")}}, and {{cssxref("border-bottom-color")}}
-
Lets you set the color of the corresponding side of the element's border.
-
{{cssxref("border-block-start-color")}} and {{cssxref("border-block-end-color")}}
-
With these, you can set the color used to draw the borders which are closest to the start and end of the block the border surrounds. In a left-to-right writing mode (such as the way English is written), the block start border is the top edge and the block end is the bottom. This differs from the inline start and end, which are the left and right edges (corresponding to where each line of text in the box begins and ends).
-
{{cssxref("border-inline-start-color")}} and {{cssxref("border-inline-end-color")}}
-
These let you color the edges of the border closest to to the beginning and the end of the start of lines of text within the box. Which side this is will vary depending on the {{cssxref("writing-mode")}}, {{cssxref("direction")}}, and {{cssxref("text-orientation")}} properties, which are typically (but not always) used to adjust text directionality based on the language being displayed. For example, if the box's text is being rendered right-to-left, then the border-inline-start-color is applied to the right side of the border.
-
- -

Other ways to use color

- -

CSS isn't the only web technology that supports color. There are graphics technologies that are available on the web which also support color.

- -
-
The HTML Canvas API
-
Lets you draw 2D bitmapped graphics in a {{HTMLElement("canvas")}} element. See our Canvas tutorial to learn more.
-
SVG (Scalable Vector Graphics)
-
Lets you draw images using commands that draw specific shapes, patterns, and lines to produce an image. SVG commands are formatted as XML, and can be embedded directly into a web page or can be placed in he page using the {{HTMLElement("img")}} element, just like any other type of image.
-
WebGL
-
The Web Graphics Library is an OpenGL ES-based API for drawing high-performance 2D and 3D graphics on the Web. See Learn WebGL for 2D and 3D graphics to find out more.
-
- -

How to describe a color

- -

In order to represent a color in CSS, you have to find a way to translate the analog concept of "color" into a digital form that a computer can use. This is typically done by breaking down the color into components, such as how much of each of a set of primary colors to mix together, or how bright to make the color. As such, there are several ways you can describe color in CSS.

- -

For more detailed discussion of each of the color value types, see the reference for the CSS {{cssxref("<color>")}} unit.

- -

Keywords

- -

A set of standard color names have been defined, letting you use these keywords instead of numeric representations of colors if you choose to do so and there's a keyword representing the exact color you want to use. Color keywords include the standard primary and secondary colors (such as red, blue, or orange), shades of gray (from black to white, including colors like darkgray and lightgrey), and a variety of other blended colors including lightseagreen, cornflowerblue, and rebeccapurple.

- -

See {{SectionOnPage("/en-US/docs/Web/CSS/color_value", "Color keywords", "code")}} for a list of all available color keywords.

- -

RGB values

- -

There are three ways to represent an RGB color in CSS.

- -

Hexadecimal string notation

- -

Hexadecimal string notation represents a color using hexadecimal digits to represent each of the color components (red, green, and blue). It may also include a fourth component: the alpha channel (or opacity). Each color component can be represented as a number between 0 and 255 (0x00 and 0xFF) or, optionally, as a number between 0 and 15 (0x0 and 0xF). All components must be specified using the same number of digits. If you use the single-digit notation, the final color is computed by using each component's digit twice; that is, "#D" becomes "#DD" when drawing.

- -

A color in hexadecimal string notation always begins with the character "#". After that come the hexadecimal digits of the color code. The string is case-insensitive.

- -
-
"#rrggbb"
-
Specifies a fully-opaque color whose red component is the hexadecimal number 0xrr, green component is 0xgg, and blue component is 0xbb.
-
"#rrggbbaa"
-
Specifies a color whose red component is the hexadecimal number 0xrr, green component is 0xgg, and blue component is 0xbb. The alpha channel is specified by 0xaa; the lower this value is, the more translucent the color becomes.
-
"#rgb"
-
Specifies a color whose red component is the hexadecimal number 0xrr, green component is 0xgg, and blue component is 0xbb.
-
"#rgba"
-
Specifies a color whose red component is the hexadecimal number 0xrr, green component is 0xgg, and blue component is 0xbb. The alpha channel is specified by 0xaa; the lower this value is, the more translucent the color becomes.
-
- -

As an example, you can represent the opaque color bright blue as "#0000ff" or "#00f". To make it 25% opaque, you can use "#0000ff44" or "#00f4".

- -

RGB functional notation

- -

RGB (Red/Green/Blue) functional notation, like hexadecimal string notation, represents colors using their red, green, and blue components (as well as, optionally, an alpha channel component for opacity). However, instead of using a string, the color is defined using the CSS function {{cssxref("color_value", "rgb()", "#rgb()")}}. This function accepts as its input parameters the values of the red, green, and blue components and an optional fourth parameter, the value for the alpha channel.

- -

Legal values for each of these parameters are:

- -
-
red, green, and blue
-
Each must be an {{cssxref("<integer>")}} value between 0 and 255 (inclusive), or a {{cssxref("<percentage>")}} from 0% to 100%.
-
alpha
-
The alpha channel is a number between 0.0 (fully transparent) and 1.0 (fully opaque). You can also specify a percentage where 0% is the same as 0.0 and 100% is the same as 1.0.
-
- -

For example, a bright red that's 50% opaque can be represented as rgb(255, 0, 0, 0.5) or rgb(100%, 0, 0, 50%).

- -

HSL functional notation

- -

Designers and artists often prefer to work using the {{interwiki("wikipedia", "HSL and HSV", "HSL")}} (Hue/Saturation/Luminosity) color method. On the web, HSL colors are represented using HSL functional notation. The hsl() CSS function is very similar to the rgb() function in usage otherwise.

- -
-
HSL color cylinder -
Figure 1. An HSL color cylinder. Hue defines the actual color based on the position along a circular color wheel representing the colors of the visible spectrum. Saturation is a percentage of how much of the way between being a shade of gray and having the maximum possible amount of the given hue. As the value of luminance (or lightness) increases, the color transitions from the darkest possible to the brightest possible (from black to white). Image courtesy of user SharkD on Wikipedia, distributed under the CC BY-SA 3.0 license.
-
-
- -

The value of the hue (H) component of an HSL color is an angle from red around through yellow, green, cyan, blue, and magenta (ending up back at red again at 360°) that identifies what the base color is. The value can be specified in any {{cssxref("<angle>")}} unit supported by CSS, including degrees (deg), radians (rad), gradians (grad), or turns (turn). But this doesn't control how vivid or dull, or how bright or dark the color is.

- -

The saturation (S) component of the color specifies what percentage of the final color is comprised of the specified hue. The rest is defined by the grey level provided by the luminance (L) component.

- -

Think of it like creating the perfect paint color:

- -
    -
  1. You start with base paint that's the maximum intensity possible for a given color, such as  the most intense blue that can be represented by the user's screen. This is the hue (H) component: a value representing the angle around the color wheel for the vivid hue we want to use as our base.
    2. -
  2. Then select a greyscale paint that corresponds how bright you want the color to be; this is the luminance. Do you want it to be very bright and nearly white, or very dark and closer to black, or somewhere in between? This is specified using a percentage, where 0% is perfectly black and 100% is perfectly white. (regardless of the saturation or hue). In between values are a literal grey area.
    3. -
  3. Now that you have a grey paint and a perfectly vivid color, you need to mix them together. The saturation (S) component of the color indicates what percentage of the final color should be comprised of that perfectly vivid color. The rest of the final color is made up of the grey paint that represents the saturation.
    4. -
- -

You can also optionally include an alpha channel, to make the color less than 100% opaque.

- -

Here are some sample colors in HSL notation:

- -
- - -

{{EmbedLiveSample("hsl-swatches", 300, 260)}}

-
- -
-

Note that when you omit the hue's unit, it's assumed to be in degrees (deg).

-
- -

Using color

- -

Now that you know what CSS properties exist that let you apply color to elements and the formats you can use to describe colors, you can put this together to begin to make use of color. As you may have seen from the list under {{anch("Things that can have color")}}, there are plenty of things you can color with CSS. Let's look at this from two sides: using color within a {{Glossary("stylesheet")}}, and adding and changing color using {{Glossary("JavaScript")}} code to alter the styles of elements.

- -

Specifying colors in stylesheets

- -

The easiest way to apply color to elements—and the way you'll usually do it—is to simply specify colors in the CSS that's used when rendering elements. While we won't use every single property mentioned previously, we'll look at a couple of examples. The concept is the same anywhere you use color.

- -

Let's take a look at an example, starting by looking at the results we're trying to achieve:

- -
{{EmbedLiveSample("Specifying_colors_in_stylesheets", 650, 150)}}
- -

HTML

- -

The HTML responsible for creating the above example is shown here:

- -
<div class="wrapper">
-  <div class="box boxLeft">
-    <p>
-      This is the first box.
-    </p>
-  </div>
-  <div class="box boxRight">
-    <p>
-      This is the second box.
-    </p>
-  </div>
-</div>
- -

This is pretty simple, using a {{HTMLElement("div")}} as a wrapper around the contents, which consists of two more <div>s, each styled differently with a single paragraph ({{HTMLElement("p")}}) in each box.

- -

The magic happens, as usual, in the CSS, where we'll apply colors define the layout for the HTML above.

- -

CSS

- -

We'll look at the CSS to create the above results a piece at a time, so we can review the interesting parts one by one.

- -
.wrapper {
-  width: 620px;
-  height: 110px;
-  margin: 0;
-  padding: 10px;
-  border: 6px solid mediumturquoise;
-}
- -

The .wrapper class is used to assign styles to the {{HTMLElement("div")}} that encloses all of our other content. This establishes thesize of the container using {{cssxref("width")}} and {{cssxref("height")}} as well as its {{cssxref("margin")}} and {{cssxref("padding")}}.

- -

Of more interest to our discussion here is the use of the {{cssxref("border")}} property to establish a border around the outside edge of the element. This border is a solid line, 6 pixels wide, in the color mediumturquoise.

- -

Our two colored boxes share a number of properties in common, so next we establish a class, .box, that defines those shared properties:

- -
.box {
-  width: 290px;
-  height: 100px;
-  margin: 0;
-  padding: 4px 6px;
-  font: 28px "Marker Felt", "Zapfino", cursive;
-  display: flex;
-  justify-content: center;
-  align-items: center;
-}
- -

In brief, .box establishes the size of each box, as well as the configuration of the font used within. We also take advantage of CSS Flexbox to easily center the contents of each box. We enable flex mode using {{cssxref("display", "display: flex")}}, and set both {{cssxref("justify-content")}} and {{cssxref("align-items")}} to center. Then we can create a class for each of the two boxes that defines the propeties that differ between the two.

- -
.boxLeft {
-  float: left;
-  background-color: rgb(245, 130, 130);
-  outline: 2px solid darkred;
-}
- -

The .boxLeft class—which, cleverly, is used to style the box on the left—floats the box to the left, then sets up the colors:

- - - -
.boxRight {
-  float: right;
-  background-color: hsl(270deg, 50%, 75%);
-  outline: 4px dashed rgb(110, 20, 120);
-  color: hsl(0deg, 100%, 100%);
-  text-decoration: underline wavy #88ff88;
-  text-shadow: 2px 2px 3px black;
-}
- -

Finally, the .boxRight class describes the unique properties of the box that's drawn on the right. It's configured to float the box to the right so that it appears next to the previous box. Then the following colors are established:

- - - -

Letting the user pick a color

- -

There are many situations in which your web site may need to let the user select a color. Perhaps you have a customizable user interface, or you're implementing a drawing app. Maybe you have editable text and need to let the user choose the text color. Or perhaps your app lets the user assign colors to folders or items. Although historically it's been necessary to implement your own {{interwiki("wikipedia", "color picker")}}, HTML now provides support for browsers to provide one for your use through the {{HTMLElement("input")}} element, by using "color" as the value of its {{htmlattrxref("type", "input")}} attribute.

- -

The <input> element represents a color only in the {{anch("Hexadecimal string notation", "hexadecimal string notation")}} covered above.

- -

Example: Picking a color

- -

Let's look at a simple example, in which the user can choose a color. As the user adjusts the color, the border around the example changes to reflect the new color. After finishing up and picking the final color, the color picker's value is displayed.

- -

{{EmbedLiveSample("Example_Picking_a_color", 525, 275)}}

- -
-

On macOS, you indicate that you've finalized selection of the color by closing the color picker window.

-
- -

HTML

- -

The HTML here creates a box that contains a color picker control (with a label created using the {{HTMLElement("label")}} element) and an empty paragraph element ({{HTMLElement("p")}}) into which we'll output some text from our JavaScript code.

- -
<div id="box">
-  <label for="colorPicker">Border color:</label>
-  <input type="color" value="#8888ff" id="colorPicker">
-  <p id="output"></p>
-</div>
- -

CSS

- -

The CSS simply establishes a size for the box and some basic styling for appearances. The border is also established with a 2-pixel width and a border color that won't last, courtesy of the JavaScript below...

- -
#box {
-  width: 500px;
-  height: 200px;
-  border: 2px solid rgb(245, 220, 225);
-  padding: 4px 6px;
-  font: 16px "Lucida Grande", "Helvetica", "Arial", "sans-serif"
-}
- -

JavaScript

- -

The script here handles the task of updating the starting color of the border to match the color picker's value. Then two event handlers are added to deal with input from the <input type="color"> element.

- -
let colorPicker = document.getElementById("colorPicker");
-let box = document.getElementById("box");
-let output = document.getElementById("output");
-
-box.style.borderColor = colorPicker.value;
-
-colorPicker.addEventListener("input", function(event) {
-  box.style.borderColor = event.target.value;
-}, false);
-
-colorPicker.addEventListener("change", function(event) {
-  output.innerText = "Color set to " + colorPicker.value + ".";
-}, false);
- -

The {{event("input")}} event is sent every time the value of the element changes; that is, every time the user adjusts the color in the color picker. Each time this event arrives, we set the box's border color to match the color picker's current value.

- -

The {{event("change")}} event is received when the color picker's value is finalized. We respond by setting the contents of the <p> element with the ID "output" to a string describing the finally selected color.

- -

Using color wisely

- -

Making the right choices when selecting colors when designing a web site can be a tricky process, especially if you aren't well-grounded in art, design, or at least basic color theory. The wrong color choice can render your site unattractive, or even worse, leave the content unreadable due to problems with contrast or conflicting colors. Worse still, if using the wrong colors can result in your content being outright unusable by people withcertain vision problems, particularly color blindness.

- -

Finding the right colors

- -

Coming up with just the right colors can be tricky, especially without training in art or design. Fortunately, there are tools available that can help you. While they can't replace having a good designer helping you make these decisions, they can definitely get you started.

- -

Base color

- -

The first step is to choose your base color. This is the color that in some way defines your web site or the subject matter of the site. Just as we associate green with the beverage {{interwiki("wikipedia", "Mountain Dew")}} and one might think of the color blue in relationship with the sky or the ocean, choosing an appropriate base color to represent your site is a good place to start. There are plenty of ways to select a base color; a few ideas include:

- - - -

When trying to decide upon a base color, you may find that browser extensions that let you select colors from web content can be particularly handy. Some of these are even specifically designed to help with this sort of work. For example, the web site ColorZilla offers an extension (Chrome / Firefox) that offers an eyedropper tool for picking colors from the web. It can also take averages of the colors of pixels in various sized areas or even a selected area of the page.

- -
-

The advantage to averaging colors can be that often what looks like a solid color is actually a surprisingly varied number of related colors all used in concert, blending to create a desired effect. Picking just one of these pixels can result in getting a color that on its own looks very out of place.

-
- -

Fleshing out the palette

- -

Once you have decided on your base color, there are plenty of online tools that can help you build out a palette of appropriate colors to use along with your base color by applying color theory to your base color to determine appropriate added colors. Many of these tools also support viewing the colors filtered so you can see what they would look like to people with various forms of color blindness. See {{anch("Color and accessibility")}} for a brief explanation of why this matters.

- -

A few examples (all free to use as of the time this list was last revised):

- - - -

When designing your palette, be sure to keep in mind that in addition to the colors these tools typically generate, you'll probably also need to add some core neutral colors such as white (or nearly white), black (or nearly black), and some number of shades of gray.

- -
-

Usually, you are far better off using the smallest number of colors possible. By using color to accentuate rather than adding color to everything on the page, you keep your content easy to read and the colors you do use have far more impact.

-
- -

Color theory resources

- -

A full review of color theory is beyond the scope of this article, but there are plenty of articles about color theory available, as well as courses you can find at nearby schools and universities. A couple of useful resources about color theory:

- -
-
Color Science (Khan Academy in association with Pixar)
-
An online course which introduces concepts such as what color is, how it's percieved, and how to use colors to express ideas. Presented by Pixar artists and designers.
-
{{interwiki("wikipedia", "Color theory")}} on Wikipedia
-
Wikipedia's entry on color theory, which has a lot of great information from a technical perspective. It's not really a resource for helping you with the color sleection process, but is still full of useful information.
-
- -

Color and accessibility

- -

There are several ways color can be an {{Glossary("accessibility")}} problem. Improper or careless use of color can result in a web site or app that a percentage of your target audience may not be able to use adequately, resulting in lost traffic, lost business, and possibly even a public relations problem. So it's important to consider your use of color carefully.

- -

You should do at least basic research into {{interwiki("wikipedia", "color blindness")}}. There are several kinds; the most common is red-green color blindness, which causes people to be unable to differentiate between the colors red and green. There are others, too, ranging from inabilities to tell the difference between certain colors to total inability to see color at all.

- -
-

The most important rule: never use color as the only way to know something. If, for example, you indicate success or failure of an operation by changing the color of a shape from white to green for success and red for failure, users with red-green color-blindness won't be able to use your site properly. Instead, perhaps use both text and color together, so that everyone can understand what's happening.

-
- -

For more information about color blindness, see the following articles:

- - - -

Palette design example

- -

Let's consider a quick example of selecting an appropriate color palette for a site. Imagine that you're building a web site for a new game that takes place on the planet Mars. So let's do a Google search for photos of Mars. Lots of good examples of Martian coloration there. We carefully avoid the mockups and the photos from movies. And we decide to use a photo taken by one of the Mars landers humanity has parked on the surface over the last few decades, since the game takes place on the planet's surface. We use a color picker tool to select a sample of the color we choose.

- -

Using an eyedropper tool, we identify a color we like and determine that the color in question is #D79C7A, which is an appropriate rusty orange-red color that's so stereotypical of the Martian surface.

- -

Having selected our base color, we need to build out our palette. We decide to use Paletton to come up with the other colors we need. Upon opening Paletton, we see:

- -

Right after loading Paletton.

- -

Next, we enter our color's hex code (D79C7A) into the "Base RGB" box at the bottom-left corner of the tool:

- -

After entering base color

- -

We now see a monochromatic palette based on the color we picked from the Mars photo. If you need a lot of related colors for some reason, those are likely to be good ones. But what we really want is an accent color. Something that will pop along side the base color. To find that, we click the "add complementary" toggle underneath the menu that lets you select the palette type (currently "Monochromatic"). Paletton computes an appropriate accent color; clicking on the accent color down in the bottom-right corner tells us that this color is #508D7C.

- -

Now with complementary colors included.

- -

If you're unhappy with the color that's proposed to you, you can change the color scheme, to see if you find something you like better. For example, if we don't like the proposed greenish-blue color, we can click the Triad color scheme icon, which presents us with the following:

- -

Triad color scheme selected

- -

That greyish blue in the top-right looks pretty good. Clicking on it, we find that it's #556E8D. That would be used as the accent color, to be used sparingly to make things stand out, such as in headlines or in the highlighting of tabs or other indicators on the site:

- -

Triad color scheme selected

- -

Now we have our base color and our accent. On top of that, we have a few complementary shades of each, just in case we need them for gradients and the like. The colors can then be exported in a number of formats so you can make use of them.

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Once you have these colors, you will probably still need to select appropriate neutral colors. Common design practice is to try to find the sweet spot where there's just enough contrast that the text is crisp and readable but not enough contrast to become harsh for the eyes. It's easy to go too far in one way or another so be sure to get feedback on your colors once you've selected them and have examples of them in use available. If the contrast is too low, your text will tend to be washed out by the background, leaving it unreadable, but if your contrast is too high, the user may find your site garish and unpleasant to look at.

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Color, backgrounds, contrast, and printing

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What looks good on screen may look very different on paper. In addition, ink can be expensive, and if a user is printing your page, they don't necessarily need all the backgrounds and such using up their precious ink when all that matters is the text itself. Most browsers, by default, remove background images when printing documents.

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If your background colors and images have been selected carefully and/or are crucial to the usefulness of the content, you can use the CSS {{cssxref("color-adjust")}} property to tell the browser that it should not make adjustments to the appearance of content.

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The default value of color-adjust, economy, indicates that the browser is allowed to make appearance changes as it deems necessary in order to try to optimize the legibility and/or print economy of the content, given the type of output device the document is being drawn onto.

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You can set color-adjust to exact to tell the browser that the element or elements on which you use it have been designed specifically to best work with the colors and images left as they are. With this set, the browser won't tamper with the appearance of the element, and will draw it as indicated by your CSS.

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Note: There is no guarantee, though, that color-adjust: exact will result in your CSS being used exactly as given. If the browser provides user preferences to change the output (such as a "don't print backgrounds" checkbox in a print dialog box), that overrides the value of color-adjust.

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See also

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