regex - JavaScript Validation for Email Id

Duplicate :

Validate email address in JavaScript?

I want to validate emailid using JavaScript. I am using following code:

var emailPat = /^(\".*\"|[A-Za-z]\w*)@(\[\d{1,3}(\.\d{1,3}){3}]|[A-Za-z]\w*(\.[A-Za-z]\w*)+)$/ ;
var emailid=document.getElementById("<%=txtEmail.ClientID %>").value; 
var matchArray = emailid.match(emailPat);
if (txtemail.value!="")
{  
  if (matchArray == null)
  {
        alert("Your email address seems to be incorrect. \n Please type the proper email address and try again.") 
        return false
  }

}

This code is working for emails like, abc@xyz.com

But when i enter valid mailid like ab.cd@xyz.com or abc@xy-z.com, it is showing alert.
What changes should I do in my coding, so it will not show alert for valid mail ids like above? Can anyone give me suggestions?