JavaScript+Email Validation

function fnCheckNotNull()
{
var m = document.getElementById("<%=txtErrorEmail.ClientID%>").value.replace(/^\s+|\s+$/g,"")
if (m != "")
{
if (m.search(/^\w+((-\w+)|(\.\w+))*\@[A-Za-z0-9]+((\.|-)[A-Za-z0-9]+)*\.[A-Za-z0-9]+$/) != -1)
{
return true;
}
else
{
alert("Invalid Email Address");
document.getElementById("<%=txtErrorEmail.ClientID%>").focus();
return false;
}
}
}