复制代码 代码如下:
<!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">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>jQuery+JavaScript 实现 table 的增加和减少</title>
<script language="javascript" src="jquery-1.7.1.min.js"></script>
</head>
<body>
<p><input type="text" value="请输入邮箱地址" id="email" id="email" /></p>
<p><input type="button" value="提交" /></p>
<script type="text/javascript">
$("#email").focus(function(){
var email_txt = $(this).val();
if (email_txt == this.defaultValue) {
$(this).val("");
}
})
$("#email").blur(function(){
var email_txt = $(this).val();
if (email_txt == "") {
$(this).val(this.defaultValue);
}
})
</script>
</body>
</html>
效果预览： 