Help with tweaking Form to simply require Contact Name field to be completed

I have a working for that has this code:

					<script type="text/javascript">
					function checkemail(){
						var str=document.myform.email_address.value;
						var filter=/^([\\w-]+(?:\\.[\\w-]+)*)@((?:[\\w-]+\\.)*\\w[\\w-]{0,66})\\.([a-z]{2,6}(?:\\.[a-z]{2})?)$/i;
						if (filter.test(str))
							testresults=true;
						else {
							alert("Please input a valid email address!");
							return false;
						}
						if(document.myform.agree.checked!=1) {
							alert("Please check the box to agree to the Terms.");
							return false;
						}
						if(document.myform.ans.value.toLowerCase()!="hot") {
							alert("Please answer security question correctly: Hot or Cold?");
							return false;
						}
						return true;
					}
		</script>

And this code:

<form action='form_handler1.php' method='post' name='myform' onSubmit="return checkemail()">

I’d simply like to add code to require that the Contact Name field be completed before Submission.
Any help will be appreciated.
Thanks