JAVASCRIPT

linking a script .js

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

how to link javascript to html

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

how to link javascript to html

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

linking html with javascript

 <script type="text/javascript" src=es4.js></script>

how to include script file in javascript

import('your-file-name.js')
//this only works for javascript files
//and with bugs or half bugs it won't work

how to connect a javascript file to html

<script src="name.js">
	//put in your javascript here
</script>

how to include script file in javascript with javascript

check this link:
https://stackoverflow.com/questions/950087/how-do-i-include-a-javascript-file-in-another-javascript-file
it wil tell you it in all js variants (including jQuery and node.js)