shaunhey/upc2.html

## upc2.html
<html>
<head>
<script type="text/javascript">

var NONE  = 0;
var PLUS  = 1;
var MINUS = -1;

function calculateWeightedProduct(digit, weight, sign) {
  var value = digit * weight;
	var tens = Math.floor(value / 10);
	value += sign * tens;
	return value % 10;
}

function calculateFourDigitPriceCheckDigit(price) {
	var checkDigit = 0;

	checkDigit += calculateWeightedProduct(price[0], 2, MINUS);
	checkDigit += calculateWeightedProduct(price[1], 2, MINUS);
	checkDigit += calculateWeightedProduct(price[2], 3, NONE);
	checkDigit += calculateWeightedProduct(price[3], 5, MINUS);
	checkDigit *= 3;

	return checkDigit % 10;
}

function calculateFiveDigitPriceCheckDigit(price) {
	var checkDigit = 0;

	checkDigit += calculateWeightedProduct(price[0], 5, PLUS);
	checkDigit += calculateWeightedProduct(price[1], 2, MINUS);
	checkDigit += calculateWeightedProduct(price[2], 5, MINUS);
	checkDigit += calculateWeightedProduct(price[3], 5, PLUS);
	checkDigit += calculateWeightedProduct(price[4], 2, MINUS);
	checkDigit = (10 - (checkDigit % 10)) % 10;

	if (checkDigit) {
		for (var i = 0; i < 10; i++) {
			if (calculateWeightedProduct(i, 5, MINUS) == checkDigit) {
				checkDigit = i;
				break;
			}
		}
	}

	return checkDigit;
}

function calculateCheckDigit() {
	var priceTextBox = document.getElementById("price");
	var checkDigitTextBox = document.getElementById("checkDigit");

	if (priceTextBox.value.length == 4) {
		checkDigitTextBox.value = calculateFourDigitPriceCheckDigit(priceTextBox.value);
	} else if (priceTextBox.value.length == 5) {
		checkDigitTextBox.value = calculateFiveDigitPriceCheckDigit(priceTextBox.value);
	} else {
		checkDigitTextBox.value = "";
	}
}
</script>
</head>
<body>
<b>Price field check digit calculator</b><br>
This tool calculates the price check digit for UPC2/NSC2 barcodes with 4 and 5 digit price fields.<br><br>
Price:<br>
<input label="Price" type="text" id="price" size="5" maxlength="5" onkeyup="calculateCheckDigit()"><br><br>
Price Check Digit:<br>
<input type="text" id="checkDigit" size="1" readonly><br>
</body>
</html>
	<html>
	<head>
	<script type="text/javascript">

	var NONE = 0;
	var PLUS = 1;
	var MINUS = -1;

	function calculateWeightedProduct(digit, weight, sign) {
	var value = digit * weight;
	var tens = Math.floor(value / 10);
	value += sign * tens;
	return value % 10;
	}

	function calculateFourDigitPriceCheckDigit(price) {
	var checkDigit = 0;

	checkDigit += calculateWeightedProduct(price[0], 2, MINUS);
	checkDigit += calculateWeightedProduct(price[1], 2, MINUS);
	checkDigit += calculateWeightedProduct(price[2], 3, NONE);
	checkDigit += calculateWeightedProduct(price[3], 5, MINUS);
	checkDigit *= 3;

	return checkDigit % 10;
	}

	function calculateFiveDigitPriceCheckDigit(price) {
	var checkDigit = 0;

	checkDigit += calculateWeightedProduct(price[0], 5, PLUS);
	checkDigit += calculateWeightedProduct(price[1], 2, MINUS);
	checkDigit += calculateWeightedProduct(price[2], 5, MINUS);
	checkDigit += calculateWeightedProduct(price[3], 5, PLUS);
	checkDigit += calculateWeightedProduct(price[4], 2, MINUS);
	checkDigit = (10 - (checkDigit % 10)) % 10;

	if (checkDigit) {
	for (var i = 0; i < 10; i++) {
	if (calculateWeightedProduct(i, 5, MINUS) == checkDigit) {
	checkDigit = i;
	break;
	}
	}
	}

	return checkDigit;
	}

	function calculateCheckDigit() {
	var priceTextBox = document.getElementById("price");
	var checkDigitTextBox = document.getElementById("checkDigit");

	if (priceTextBox.value.length == 4) {
	checkDigitTextBox.value = calculateFourDigitPriceCheckDigit(priceTextBox.value);
	} else if (priceTextBox.value.length == 5) {
	checkDigitTextBox.value = calculateFiveDigitPriceCheckDigit(priceTextBox.value);
	} else {
	checkDigitTextBox.value = "";
	}
	}
	</script>
	</head>
	<body>
	<b>Price field check digit calculator</b><br>
	This tool calculates the price check digit for UPC2/NSC2 barcodes with 4 and 5 digit price fields.<br><br>
	Price:<br>
	<input label="Price" type="text" id="price" size="5" maxlength="5" onkeyup="calculateCheckDigit()"><br><br>
	Price Check Digit:<br>
	<input type="text" id="checkDigit" size="1" readonly><br>
	</body>
	</html>