<script type="text/javascript">
function validate() {
    var x = document.forms["form"]["firstname"].value;
    var y = document.forms["form"]["lastname"].value;
    var m =  document.forms["myForm"]["mobile"].value;
    var email = document.forms["myForm"]["email"].value;
    var atpos = email.indexOf("@");
    var dotpos = email.lastIndexOf(".");

    if (x == null || x == "") {
        alert("First name must be filled out");
        return false;
    }

   else if (y == null || y == ""){
        alert("Last name must be filled out");
        return false;
    }

   else if (IsNumeric(m) == false || m<0 || m == null || m == ""){
    alert("Not a valid Mobile Number");
        return false;
   }


    else if (atpos< 1 || dotpos<atpos+2 || dotpos+2>=x.length) {
        alert("Not a valid e-mail address");
        return false;
    }


}
</script>