link between html and javascript code example
Example 1: link javascript to html
<script src="index.js"> </script>
Example 2: javascript link in html
<script type="text/javascript" src="./der/pfad/zu/der/datei.js"></script>
<script src="index.js"> </script>
<script type="text/javascript" src="./der/pfad/zu/der/datei.js"></script>