javascript validation for email - id

function email()
{

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 (matchArray == null)
{
alert("Your email address seems incorrect. Please try again.");
document.getElementById("<%=txtEmail.ClientID %>").focus();
return false;
}
}