EAN13 (barcode) check digit user macro

[Reto Eggenberger]

Hi

I want to make a simple user macro, which calculates the ean13 check digit with javascript. But I'm absolutely not used to velocity. Maybe someone can give me a jump start ...

I've found this javascript code to calculate the 13th digit:

function getLastEan13Digit(ean) {
 if (!ean || ean.length !== 12) throw new Error('Invalid EAN 13, should have 12 digits');
 const multiply = [1, 3];
 let total = 0;
 ean.split('').forEach((letter, index) => {
 total += parseInt(letter, 10) * multiply[index % 2];
 });
 const base10Superior = Math.ceil(total / 10) * 10;
 return base10Superior - total;
}

How can I display this script result on the page?

I guess I have to wrap it in a script tag and I tried this:

getLastEan13Digit('$paramEAN13');

<script type="text/javascript">
function getLastEan13Digit(ean) {
 if (!ean || ean.length !== 12) throw new Error('Invalid EAN 13, should have 12 digits')
 const multiply = [1, 3];
 let total = 0;
 ean.split('').forEach((letter, index) => {
 total += parseInt(letter, 10) * multiply[index % 2];
 })
 const base10Superior = Math.ceil(total / 10) * 10;
 return = base10Superior - total;
}
</script>

But of course this doesn't execute the script.

Thx for any hints. 

[Reto Eggenberger · Accepted solution]

Got it.

Just use normal jQuery syntax ...

<div id="result">Test</div>

<script type="text/javascript">
jQuery(document).ready(function () {
 jQuery('#result').text('$paramEAN13'+getLastEan13Digit('$paramEAN13'));
});

function getLastEan13Digit(ean) {
 if (!ean || ean.length !== 12) throw new Error('Invalid EAN 13, should have 12 digits')
 const multiply = [1, 3];
 let total = 0;
 ean.split('').forEach((letter, index) => {
 total += parseInt(letter, 10) * multiply[index % 2];
 })
 const base10Superior = Math.ceil(total / 10) * 10;
 return base10Superior - total;
};
</script>