onfocus 事件

定义和用法

onfocus 事件在对象获得焦点时发生。

语法

onfocus="SomeJavaScriptCode"
参数 描述
SomeJavaScriptCode 必需。规定该事件发生时执行的 JavaScript。

支持该事件的 HTML 标签:

<a>, <acronym>, <address>, <area>, <b>, <bdo>, <big>, <blockquote>, <button>, 
<caption>, <cite>, <dd>, <del>, <dfn>, <div>, <dl>, <dt>, <em>, <fieldset>, 
<form>, <frame>, <frameset>, <h1> to <h6>, <hr>, <i>, <iframe>, <img>, <input>, 
<ins>, <kbd>, <label>, <legend>, <li>, <object>, <ol>, <p>, <pre>, <q>, 
<samp>, <select>, <small>, <span>, <strong>, <sub>, <sup>, <table>, <tbody>, 
<td>, <textarea>, <tfoot>, <th>, <thead>, <tr>, <tt>, <ul>, <var>

支持该事件的 JavaScript 对象:

button, checkbox, fileUpload, layer, frame, password, radio, reset, select, submit, 
text, textarea, window

实例

在本例中,当输入框获得焦点时,其背景颜色将改变:

<html>
<head>
<script type="text/javascript">
function setStyle(x)
{
document.getElementById(x).style.background="yellow"
}
</script>
</head>

<body>

First name: <input type="text"
onfocus="setStyle(this.id)" id="fname" />
<br />
Last name: <input type="text"
onfocus="setStyle(this.id)" id="lname" />

</body>
</html>

输出:

First name:

Last name:

TIY

onfocus
如何使用 onfocus。