function updateTotal() {

	var f = document.shirts; //form
	
	f.subtotal_1.value = calculate(f.number_1.value, whichShirt(f.type_1.value));
	f.subtotal_2.value = calculate(f.number_2.value, whichShirt(f.type_2.value));
	f.subtotal_3.value = calculate(f.number_3.value, whichShirt(f.type_3.value));

	f.total.value = parseFloat(f.subtotal_1.value) + parseFloat(f.subtotal_2.value) + parseFloat(f.subtotal_3.value);

}

function whichShirt(val) {  //return the cost of the shirt

	if (val == "Golf Shirts") {
		return 28;
	}
	else if (val == "Long Sleeve T") { //Long Sleeve T
		return 18;
	}
	else {
		return 0;
	}
}
	
function calculate(num, eachPrice) { //if num is empty, then set it to 0

	if (num == "") {
		num = 0;
	}

	return parseFloat(num*eachPrice);
}
	

function onReset() {  //reset button was click

	for (var i=0; i<document.shirts.length-2; i++) {

		document.shirts[i].value = "";
	}
}

function checkForm() {

	var f = document.shirts; //form
	var errorMessage = ""; //error message

	if ( f.name.value == "" ) { //if name empty
		errorMessage += "\tName\n";
	}

	if ( f.address1.value == "" )	{ //address
		errorMessage += "\tAddress\n";
	}

	if ( f.city.value == "" ) { //city
		errorMessage += "\tCity\n";
	}

	if ( f.state.value == "" ) { //state
		errorMessage += "\tState\n";
	}

	if ( f.zip.value == "" ) { //zip
		errorMessage += "\tZip Code\n";
	}

	if ( f.phone.value == "" ) { //phone number
		errorMessage += "\tPhone\n";
	}

	if ( f.number_1.value != "" ) {
		if ( f.type_1.value == "" ) {
			errorMessage += "\tType\n";
		}
		
		if ( f.size_1.value == "" ) {
			errorMessage += "\tSize\n";
		}

		if ( f.color_1.value == "" ) {
			errorMessage += "\tColor\n";
		}
	}

	if ( f.number_2.value != "" ) {
		if ( f.type_2.value == "" ) {
			errorMessage += "\tType\n";
		}
		
		if ( f.size_2.value == "" ) {
			errorMessage += "\tSize\n";
		}

		if ( f.color_2.value == "" ) {
			errorMessage += "\tColor\n";
		}
	}

	if ( f.number_3.value != "" ) {
		if ( f.type_3.value == "" ) {
			errorMessage += "\tType\n";
		}
		
		if ( f.size_3.value == "" ) {
			errorMessage += "\tSize\n";
		}

		if ( f.color_3.value == "" ) {
			errorMessage += "\tColor\n";
		}
	}

	if ( errorMessage != "" ) { // there's error
		alert ( "Please fill in the following fields:\n\n"  + errorMessage );
		return false;
	}
	else {
		updateTotal();

		for (var i=0; i<f.length(); i++) {
			if (f[i].disabled == true) {
				f[i].disabled = false;
				alert(i);
			}
		}
		return true;
	}

} //end of function checkForm()