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JavaScript onkeydown 事件

作者:w3pop.com 翻译/整理:w3pop.com 发布:2007-04-28 浏览:4142 :: ::

Definition and Usage
定义与用法

The onkeydown event occurs when a keyboard key is pressed.
当按下一个键盘按键时触发onkeydown事件

Syntax
语法

onkeydown="所要执行的脚本"

Parameter
参数		 Description
注释
SomeJavaScriptCode
所要执行的脚本		 Required. Specifies a JavaScript to be executed when the event occurs.
必选项。当事件触发时所要执行的脚本

Supported by the following HTML tags:
所支持的HTML标签：

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

Supported by the following JavaScript objects:
所支持的JavaScript对象：

document, image, link, textarea

Tips and Notes
注意

Browser differences: Internet Explorer uses event.keyCode to retrieve the character that was pressed and Netscape/Firefox/Opera uses event.which.
不同浏览器：IE用event.keyCode来获取被按下的按键值，而NetScape/FireFox/Opera用的则是event.which

Example
实例

In this example the user cannot type numbers into the input field:
在下面的例子中，用户将无法向文本框内输入数字：

<html>
<body>
<script type="text/javascript">
function noNumbers(e)
{
var keynum
var keychar
var numcheck
if(window.event) // IE
{
keynum = e.keyCode
}
else if(e.which) // Netscape/Firefox/Opera
{
keynum = e.which
}
keychar = String.fromCharCode(keynum)
numcheck = /d/
return !numcheck.test(keychar)
}
</script>
<form>
<input type="text" onkeydown="return noNumbers(event)" />
</form>
</html>

The output of the code above will be:
输出结果为：

Try-It-Yourself Demos
互动演练

onkeydown
How to use onkeydown.
如何应用onkeydown

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