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---
title: String
slug: Web/JavaScript/Referencje/Obiekty/String
tags:
- JavaScript
- String
translation_of: Web/JavaScript/Reference/Global_Objects/String
---
<p>{{JSRef}}</p>
<h2 id="Podsumowanie" name="Podsumowanie">Podsumowanie</h2>
<p>Tworzy obiekt pozwalający działać na ciągach znaków.</p>
<h2 id="Tworzony_przez" name="Tworzony_przez">Składnia</h2>
<p>Literały znakowe są postaci:</p>
<pre class="syntaxbox notranslate">'string text'
"string text"
"中文 español English हिन्दी العربية português বাংলা русский 日本語 ਪੰਜਾਬੀ 한국어 தமிழ்"
</pre>
<p>Beside regular, printable characters, special characters can be encoded using escape notation:</p>
<table class="standard-table">
<thead>
<tr>
<th scope="col">Code</th>
<th scope="col">Output</th>
</tr>
</thead>
<tbody>
<tr>
<td><code>\0</code></td>
<td>the NUL character</td>
</tr>
<tr>
<td><code>\'</code></td>
<td>single quote</td>
</tr>
<tr>
<td><code>\"</code></td>
<td>double quote</td>
</tr>
<tr>
<td><code>\\</code></td>
<td>backslash</td>
</tr>
<tr>
<td><code>\n</code></td>
<td>new line</td>
</tr>
<tr>
<td><code>\r</code></td>
<td>carriage return</td>
</tr>
<tr>
<td><code>\v</code></td>
<td>vertical tab</td>
</tr>
<tr>
<td><code>\t</code></td>
<td>tab</td>
</tr>
<tr>
<td><code>\b</code></td>
<td>backspace</td>
</tr>
<tr>
<td><code>\f</code></td>
<td>form feed</td>
</tr>
<tr>
<td><code>\uXXXX</code></td>
<td>unicode codepoint</td>
</tr>
<tr>
<td><code>\xXX</code></td>
<td>the Latin-1 character</td>
</tr>
</tbody>
</table>
<p>Or, using the <code>String</code> global object directly:</p>
<pre class="syntaxbox notranslate">String(thing)
new String(thing)
</pre>
<h3 id="Parametry" name="Parametry">Parametry</h3>
<dl>
<dt><code>thing</code></dt>
<dd>Dowolny łańcuch znaków.</dd>
</dl>
<h2 id="Opis" name="Opis">Opis</h2>
<p>trings are useful for holding data that can be represented in text form. Some of the most-used operations on strings are to check their {{jsxref("String.length", "length")}}, to build and concatenate them using the <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/String_Operators">+ and += string operators</a>, checking for the existence or location of substrings with the {{jsxref("String.prototype.indexOf()", "indexOf()")}} method, or extracting substrings with the {{jsxref("String.prototype.substring()", "substring()")}} method.</p>
<h3 id="Character_access" name="Character_access">Character access</h3>
<p>There are two ways to access an individual character in a string. The first is the {{jsxref("String.prototype.charAt()", "charAt()")}} method:</p>
<pre class="brush: js notranslate">return 'cat'.charAt(1); // returns "a"</pre>
<div class="line-number" style="top: 0px;"></div>
<p>The other way (introduced in ECMAScript 5) is to treat the string as an array-like object, where individual characters correspond to a numerical index:</p>
<pre class="brush: js notranslate">return 'cat'[1]; // returns "a"</pre>
<div class="line-number" style="top: 0px;"></div>
<p>For character access using bracket notation, attempting to delete or assign a value to these properties will not succeed. The properties involved are neither writable nor configurable. (See {{jsxref("Object.defineProperty()")}} for more information.)</p>
<h3 id="Comparing_strings" name="Comparing_strings">Comparing strings</h3>
<p>C developers have the <code>strcmp()</code> function for comparing strings. In JavaScript, you just use the <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Comparison_Operators">less-than and greater-than operators</a>:</p>
<pre class="brush: js notranslate">var a = 'a';
var b = 'b';
if (a < b) { // true
print(a + ' is less than ' + b);
} else if (a > b) {
print(a + ' is greater than ' + b);
} else {
print(a + ' and ' + b + ' are equal.');
}</pre>
<p>A similar result can be achieved using the {{jsxref("String.prototype.localeCompare()", "localeCompare()")}} method inherited by <code>String</code> instances.</p>
<h3 id="Distinction_between_string_primitives_and_String_objects">Distinction between string primitives and <code>String</code> objects</h3>
<p>Note that JavaScript distinguishes between <code>String</code> objects and primitive string values. (The same is true of {{jsxref("Global_Objects/Boolean", "Boolean")}} and {{jsxref("Global_Objects/Number", "Numbers")}}.)</p>
<p>String literals (denoted by double or single quotes) and strings returned from <code>String</code> calls in a non-constructor context (i.e., without using the {{jsxref("Operators/new", "new")}} keyword) are primitive strings. JavaScript automatically converts primitives to <code>String</code> objects, so that it's possible to use <code>String</code> object methods for primitive strings. In contexts where a method is to be invoked on a primitive string or a property lookup occurs, JavaScript will automatically wrap the string primitive and call the method or perform the property lookup.</p>
<pre class="brush: js notranslate">var s_prim = 'foo';
var s_obj = new String(s_prim);
console.log(typeof s_prim); // Logs "string"
console.log(typeof s_obj); // Logs "object"</pre>
<div class="line-number" style="top: 76px;"></div>
<p>String primitives and <code>String</code> objects also give different results when using {{jsxref("Global_Objects/eval", "eval()")}}. Primitives passed to <code>eval</code> are treated as source code; <code>String</code> objects are treated as all other objects are, by returning the object. For example:</p>
<pre class="brush: js notranslate">var s1 = '2 + 2'; // creates a string primitive
var s2 = new String('2 + 2'); // creates a String object
console.log(eval(s1)); // returns the number 4
console.log(eval(s2)); // returns the string "2 + 2"</pre>
<p>For these reasons, code may break when it encounters <code>String</code> objects when it expects a primitive string instead, although generally authors need not worry about the distinction.</p>
<p>A <code>String</code> object can always be converted to its primitive counterpart with the {{jsxref("String.prototype.valueOf()", "valueOf()")}} method.</p>
<pre class="brush: js notranslate">console.log(eval(s2.valueOf())); // returns the number 4</pre>
<div class="note"><strong>Note:</strong> For another possible approach to strings in JavaScript, please read the article about <a href="https://developer.mozilla.org/en-US/Add-ons/Code_snippets/StringView"><code>StringView</code> — a C-like representation of strings based on typed arrays</a>.</div>
<h2 id="W.C5.82asno.C5.9Bci" name="W.C5.82asno.C5.9Bci">Własności</h2>
<dl>
<dt>{{jsxref("String.prototype")}}</dt>
<dd>Pozwala na dodawanie własności do obiektu <code>String</code>.</dd>
</dl>
<div>{{jsOverrides("Function", "Properties", "prototype")}}</div>
<h2 id="Metody">Metody</h2>
<dl>
<dt>{{jsxref("String.fromCharCode()")}}</dt>
<dd>Zwraca łańcuch znaków stworzony przez podaną sekwencję kodów Unicode.</dd>
<dt>{{jsxref("String.fromCodePoint()")}} {{experimental_inline}}</dt>
<dd>Returns a string created by using the specified sequence of code points.</dd>
<dt>{{jsxref("String.raw()")}} {{experimental_inline}}</dt>
<dd>Returns a string created from a raw template string.</dd>
</dl>
<div>{{jsOverrides("Function", "Methods", "fromCharCode", "fromCodePoint", "raw")}}</div>
<h2 id="Przyk.C5.82ady" name="Przyk.C5.82ady">Przykłady</h2>
<h3 id="Example_String_conversion">Example: String conversion</h3>
<p>It's possible to use <code>String</code> as a "safer" {{jsxref("String.prototype.toString()", "toString()")}} alternative, as although it still normally calls the underlying <code>toString()</code>, it also works for {{jsxref("null")}} and {{jsxref("undefined")}}. For example:</p>
<pre class="brush: js notranslate">var outputStrings = [];
for (var i = 0, n = inputValues.length; i < n; ++i) {
outputStrings.push(String(inputValues[i]));
}</pre>
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