function isNumberKey(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode
if (charCode > 31 && (charCode < 48 || charCode > 57))
return false;

return true;
}
	  
function ChkForm() {
if (document.form.Naam.value.length < 1) {
alert("Please Enter Your Name");
document.form.Naam.focus()
return false;
}
if (document.form.Emailadres.value.length < 1) {
alert("Please Enter Your Email");
document.form.Emailadres.focus()
return false;
}

return true;
}