</p> <p><script type="text/javascript"></p> <p>var flashTimer = null;</p> <p>var flashState = flashCount = 0;</p> <p>$ = function(el){ return document.getElementById(el); }</p> <p>function flash(el)</p> <p>{</p> <p> if(flashState == 1)</p> <p> {</p> <p> $(el).style.backgroundColor = "#FFF";</p> <p> flashState = 0;</p> <p> }</p> <p> else</p> <p> {</p> <p> $(el).style.backgroundColor = "#F00"; </p> <p> flashState = 1;</p> <p> } </p> <p> if(flashCount == 5)</p> <p> {</p> <p> $(el).focus();</p> <p> clearTimeout(flashTimer);</p> <p> flashCount = flashState = 0;</p> <p> }</p> <p> else</p> <p> {</p> <p> flashTimer = setTimeout("flash('"+el+"')",50);</p> <p> flashCount++;</p> <p> }</p> <p>}</p> <p></script></p> <select id="oSel"> <p><option>请选择分类</option></p> <p><option>分类A</option></p> <p><option>分类B</option></p> </select> <p><button onclick="if($('oSel').selectedIndex==0){flash('oSel');}else{alert('胜利提交！：）')}">Test</button></p> <p> [Ctrl+A 全部选择 提示：你可先修改部分代码，再按运行]