源自：http://www.fzs8.net/Java/JavaScript/2007-05-25/3969.html
The onkeydown event occurs when a keyboard key is pressed or held down. 当按下或按住键盘的按键时触发onkeydown事件。
οnkeypress="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
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.keCode方法获取当前被按下的键盘按键值，而NetScape/FireFox/Opera用的则是event.which
In this example the user cannot type numbers into the input field: 在下面的例子中，用户将无法在文本框内输入数字：
<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" οnkeypress="return noNumbers(event)" /> </form> </html> 相关资源：敏捷开发V1.0.pptx
