Dead Simple Javascript Error Checking

function quickSubmit() {
  errors = "";
	// the nasty error string
 
	if (document.contactus.firstName.value == "") {
		errors += "First Name\n";
		//alert(errors);
	}
 
	if (document.contactus.lastName.value == "") {
		errors+= "Last Name\n";
	}
	if (document.contactus.address1.value == "") {
		errors+= "Address\n";
	}
	if (document.contactus.city.value == "") {
		errors+= "City\n";
	}
	if (document.contactus.state.value == "") {
		errors+= "State\n";
	}
	if (document.contactus.zip.value == "") {
		errors+= "Zip\n";
	}
	if (document.contactus.phone.value == "") {
		errors+= "Phone\n";
	}
	if (document.contactus.email.value == "") {
		errors+= "Email\n";
	}
	if (errors == "") {
		document.contactus.submit();
	} else {
		alert("Please fill in the following fields:\n" + errors);
	}
 
}