要求：搜索框获取焦点的时候如果里面的内容是“请输入关键字”，则清空，否则不清空
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head><meta http-equiv="Content-Type" content="text/html;charset=UTF-8"><title>搜索文本框效果</title><script type="text/javascript" src="js/jquery-1.8.3.js"></script><script type="text/javascript">//页面加载就获取焦点function Focus(){document.getElementById('text1').focus();}$(function(){$("#text1").focus(function(){$(this).select();$(this).css("background-color","orange");if(this.value=="请输入关键字！"){this.value="";}})$("#text1").blur(function(){$(this).css("background-color","white");if(this.value==""){this.value="请输入关键字！";}})})</script>
</head>
<body οnlοad="Focus();">搜索：<input type="text" id="text1" value="请输入关键字！">
</body>
</html>
