use .js files in html code example
Example 1: include script in html
<script type="text/javascript" src="/path/to/script.js"></script>
Example 2: html bind js file
<script type="text/javascript" src="path-to-javascript-file.js"></script>
<script type="text/javascript" src="/path/to/script.js"></script>
<script type="text/javascript" src="path-to-javascript-file.js"></script>