files/zh-cn/conflicting/web/css/_colon_placeholder-shown/index.html


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67

---
title: ':-moz-placeholder'
slug: 'Web/CSS/:-moz-placeholder'
tags:
  - CSS
  - CSS Pseudo-class
  - CSS Reference
  - Non-standard
translation_of: 'Web/CSS/:placeholder-shown'
translation_of_original: 'Web/CSS/:-moz-placeholder'
---
<p> </p>

<div class="note"><strong>提示:</strong> <code><em>在Firefox 19+版本中</em> :-moz-placeholder</code> 伪类将被 {{ cssxref('::-moz-placeholder') }} 伪元素所替代.</div>

<div class="note"><strong>Note: </strong>The CSSWG have decided to introduce <code>:placeholder-shown</code>. This functionality will be reintroduced in Gecko at some point in the future, unprefixed and under the new name.  {{bug(1069012)}}</div>

<p>{{ CSSRef() }}{{Non-standard_header}}{{ gecko_minversion_header("2.0") }}</p>

<h2 id="Summary" name="Summary">摘要</h2>

<p><code> :-moz-placeholder</code><a href="/en/CSS/Pseudo-classes" title="Pseudo-classes">伪类</a>控制元素所显示的文字占位符<a href="/en/HTML/Forms_in_HTML#The_placeholder_attribute" title="en/HTML/HTML5/Forms in HTML5#The placeholder attribute">文字占位符</a>. 它允许开发者/设计师改变文字占位符样式. 默认的文字占位符颜色为浅灰色,当你的表单背景色为类似的颜色时它可能效果并不是很明显,那么你就可以使用这个伪类来改变文字占位符的颜色.</p>

<h2 id="示例">示例</h2>

<p>这个示例将文字占位符改变为了绿色.</p>

<pre class="brush: html">&lt;!doctype html&gt;
&lt;html&gt;
&lt;head&gt;
  &lt;title&gt;Placeholder demo&lt;/title&gt;
  &lt;style type="text/css"&gt;
    input:-moz-placeholder {
      color: green;
    }
  &lt;/style&gt;
&lt;/head&gt;
&lt;body&gt;
  &lt;input id="test" placeholder="Placeholder text!"&gt;
&lt;/body&gt;
&lt;/html&gt;
</pre>

<p><a href="/samples/cssref/moz-placeholder.html" title="https://developer.mozilla.org/samples/cssref/moz-placeholder.html">查看这个示例</a>.</p>

<h2 id="溢出">溢出</h2>

<p>在手机等设备上搜索框和表单字段经常会缩的很短,有时输入框并不能完全显示文字占位符,那么它便会被生硬的"切断".为了防止出现这种难看的效果,可以使用CSS <code>text-overflow: ellipsis;</code> 来省略一中间部分文字.</p>

<pre class="brush: css">input[placeholder] { text-overflow: ellipsis; }
::-moz-placeholder { text-overflow: ellipsis; } /* firefox 19+ */
input:-moz-placeholder { text-overflow: ellipsis; }
</pre>

<p>It was David Walsh, the man on fire who introduced this to a lot of designers. <a class="external" href="http://davidwalsh.name/placeholder-overflow" title="Placeholders and Overflow">Placeholders and Overflow</a>.</p>

<h2 id="Bugzilla" name="Bugzilla">Bugzilla</h2>

<p>{{ Bug(457801) }}</p>

<h2 id="SeeAlso" name="SeeAlso">See also</h2>

<ul>
 <li><a href="/en/HTML/HTML5/Forms_in_HTML5" title="en/HTML/HTML5/Forms in HTML5">Forms in HTML5</a></li>
 <li>{{ HTMLElement("input") }}</li>
 <li>{{ HTMLElement("textarea") }}</li>
</ul>