You’re including a .js file but you need to provide it with values from your HTML.

In your HTML

<script type="text/javascript" my_attribute_1='value_1' my_attribute_2='value_2' src="/my-script.js"></script>

In your JavaScript file

//Get attributes passed in the html script 
const script = document.currentScript
const attributes = script.attributes

var my_attribute_1 = attributes.getNamedItem('my_attribute_1').value;
alert('my_attribute_1: ' + my_attribute_1); //<Debug view it

var my_attribute_2 = attributes.getNamedItem('my_attribute_2').value;
alert('my_attribute_2: ' + my_attribute_2); //<Debug view it