<script type="text/javascript">
var stext = document.getelementbyid('mail').value;
//onblur 为控件失去焦点事件
document.getelementbyid('mail').onblur = function svalue(){
stext = this.value;
var remail =/^(?:[a-za-z0-9]+[_\-\+\.]?)*[a-za-z0-9]+@(?:([a-za-z0-9]+[_\-]?)*[a-za-z0-9]+\.)+([a-za-z]{2,})+$/;
var s=new regexp(remail);
if(s.test(stext))
{alert("邮箱正确");}
else//不正确清空
{document.getelementbyid('mail').value="";}
}
</script>