事件会在鼠标按键被松开时发生
支持该事件的 HTML 标签：<a>, <address>, <area>, <b>, <bdo>, <big>, <blockquote>, <body>, <button>, <caption>, <cite>, <code>, <dd>, <dfn>, <div>, <dl>, <dt>, <em>, <fieldset>, <form>, <h1> to <h6>, <hr>, <i>, <img>, <input>, <kbd>, <label>, <legend>, <li>, <map>, <ol>, <p>, <pre>, <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, document, link
例子：
<html><head> <script type="text/javascript"> //显示点击的标签 function labelClecked(e) { var targ; if (!e){var e = window.event; } if (e.target){targ = e.target; } else if(e.srcElement){targ = e.srcElement; } if (targ.nodeType == 3){targ = targ.parentNode; } var tname; tname=targ.tagName; alert("你点击的标签为：" + tname); } </script></head><body onmouseup="labelClecked(event)"><span>span标签</span><h1>header标签</h1><p>This is a paragraph</p></body></html>
，艰苦能磨练人的意志。
