how to create a javascript file code example

Example 1: include script in html

<script type="text/javascript" src="/path/to/script.js"></script>

Example 2: script src tag in html

<script type="text/javascript" 
         src="file.js">  
</script>

Example 3: how to add script in html head

<script src="script.js" defer></script>

<!--just add defer attribute so script will execute at last-->

Example 4: link javascript to html

<script src="index.js"> </script>