--- title: '::placeholder' slug: 'Web/CSS/::placeholder' translation_of: 'Web/CSS/::placeholder' --- <div>{{CSSRef}}{{SeeCompatTable}}</div> <p><a href="/en-US/docs/Web/CSS/Pseudo-elements">伪元素</a><strong><code>::placeholder</code></strong>可以选择一个表单元素的<a href="/en-US/docs/Web/HTML/Forms_in_HTML#The_placeholder_attribute">占位文本</a>,它允许开发者和设计师自定义<a href="/en-US/docs/Web/HTML/Forms_in_HTML#The_placeholder_attribute">占位文本</a>的样式。</p> <pre class="brush: css no-line-numbers">::placeholder { color: red; font-size: 1.5em; }</pre> <p>在使用了<code>::placeholder</code>伪元素的选择器中,仅有小一部分CSS属性可以使用,这个集合可以参考{{cssxref("::first-line")}}伪元素。</p> <h2 id="语法">语法</h2> <pre class="brush: css">{{csssyntax}} </pre> <h2 id="示例">示例</h2> <h3 id="红色文本">红色文本</h3> <h4 id="HTML">HTML</h4> <pre class="brush: html"><input placeholder="我是红色的!"></pre> <h4 id="CSS">CSS</h4> <pre class="brush: css">input::placeholder { color: red; font-size: 1.2em; font-style: italic; }</pre> <h4 id="结果">结果</h4> <p>{{ EmbedLiveSample('红色文本') }}</p> <h3 id="绿色文本">绿色文本</h3> <p> </p> <h4 id="HTML_2">HTML</h4> <pre class="brush: html"><input placeholder="而我是绿色的!"></pre> <h4 id="CSS_2">CSS</h4> <pre class="brush: css">input::placeholder { color: green; }</pre> <h4 id="结果_2">结果</h4> <p>{{EmbedLiveSample('绿色文本')}}</p> <p> </p> <h2 id="标准">标准</h2> <table class="standard-table"> <thead> <tr> <th scope="col">规范</th> <th scope="col">状态</th> <th scope="col">说明</th> </tr> </thead> <tbody> <tr> <td>{{SpecName('CSS4 Pseudo-Elements', '#placeholder-pseudo', '::placeholder')}}</td> <td>{{Spec2('CSS4 Pseudo-Elements')}}</td> <td>Initial definition</td> </tr> </tbody> </table> <h2 id="浏览器兼容性">浏览器兼容性</h2> <p>{{CompatibilityTable}}</p> <div id="compat-desktop"> <table class="compat-table"> <tbody> <tr> <th>功能</th> <th>Chrome</th> <th>Firefox (Gecko)</th> <th>Edge</th> <th>Internet Explorer</th> <th>Opera</th> <th>Safari</th> </tr> <tr> <td>基本支持</td> <td>{{CompatChrome(57)}}</td> <td>{{CompatGeckoDesktop("51.0")}}<sup>[1]</sup></td> <td>{{CompatNo}}</td> <td>{{CompatNo}}</td> <td>44</td> <td>10.1</td> </tr> <tr> <td>前缀支持</td> <td>Supported</td> <td>Supported</td> <td>Supported</td> <td>10 -ms-</td> <td>Supported</td> <td>5 -webkit-</td> </tr> </tbody> </table> </div> <div id="compat-mobile"> <table class="compat-table"> <tbody> <tr> <th>功能</th> <th>Android</th> <th>Chrome for Android</th> <th>Firefox Mobile (Gecko)</th> <th>IE Mobile</th> <th>Opera Mobile</th> <th>Safari Mobile</th> </tr> <tr> <td>基本支持</td> <td>{{CompatChrome(57)}}</td> <td>{{CompatChrome(57)}}</td> <td>{{CompatGeckoMobile("52.0")}}</td> <td>{{CompatNo}}</td> <td> </td> <td>10.3</td> </tr> <tr> <td>前缀支持</td> <td>Supported</td> <td>Supported</td> <td>Supported</td> <td>10 -ms-</td> <td>Supported</td> <td>5 -webkit-</td> </tr> </tbody> </table> </div> <p>[1] 在Gecko 51.0 {{geckoRelease("51.0")}} 以及更低的版本中,请使用 {{cssxref("::-moz-placeholder")}} 。</p> <h2 id="相似阅读">相似阅读</h2> <ul> <li>{{cssxref(":placeholder-shown")}}</li> <li>与此伪元素选择器功能相同的几个浏览器私有选择器: <ul> <li>{{cssxref("::-webkit-input-placeholder")}}</li> <li>{{cssxref("::-moz-placeholder")}}</li> <li>{{cssxref(":-ms-input-placeholder")}}</li> </ul> </li> <li><a href="/en-US/docs/Web/HTML/Forms_in_HTML">Forms in HTML</a></li> <li>{{HTMLElement("input")}}</li> <li>{{HTMLElement("textarea")}}</li> </ul>