javascript 邮箱验证代码   <script language="JavaScript">      function check_input()        {            //开始验证 var email = document.forms(0).email.value; var pattern = /^([a-zA-Z0-9_-])+@([a-zA-Z0-9_-])+(\.[a-zA-Z0-9_-])+/; chkFlag = pattern.test(email); if(chkFlag){ return true; } else { alert("邮箱地址的格式不正确！"); document.forms(0).TextBox_email.focus(); return false; }      }    </script>