I am currently using this method in the index.html file; however, I want my javascript in a separate file, not inline.

<script> ... my code </script>

After some research, I see there are server side includes which appear outdated but I'm not sure.

There are also templating engines for express.

And thirdly, I imagine there is some way to concatenate the file using node libraries.

And fourthly, there are build tools such as webpack and grunt. I am currently using webpack.

How can I parse all these options, and select the best one.