验证注册邮箱格式是否正确

function a(){
                  return "邮箱不符合命名规则，请核对后重新输入";
   }

function b(){
                  return "邮箱有效";
   }

function regExp()
   {
       var email=document.getElementById("email").value;
       var patt1=new RegExp("@");
         var patt2=new RegExp(".com");
         if((patt1.test(email)==false)||(patt2.test(email)==false)){
              document.getElementById("email_check").innerHTML=a();
              document.getElementById("button").disabled=true;
          email.focus();
    }else{
              document.getElementById("email_check").innerHTML=b();
              document.getElementById("button").disabled=false;
         }
                  
   }