Check out example codes for "link javascript html". It will help you in understanding the concepts better.

Code Example 1

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

Code Example 2

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

Code Example 3

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

Code Example 4

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

Code Example 5

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

Code Example 6

<script src="Your-JavaScript-File.js"></script> <!--If JS file is in same folder with HTML file-->

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