How to prevent caching of my Javascript file?

Configure your webserver to send caching control HTTP headers for the script.

Fake headers in the HTML documents:

1. Aren't as well supported as real HTTP headers
2. Apply to the HTML document, not to resources that it links to

<script src="test.js?random=<?php echo uniqid(); ?>"></script>

EDIT: Or you could use the file modification time so that it's cached on the client.

<script src="test.js?random=<?php echo filemtime('test.js'); ?>"></script>

Add a random query string to the src

You could either do this manually by incrementing the querystring each time you make a change:

<script src="test.js?version=1"></script>

Or if you are using a server side language, you could automatically generate this:

ASP.NET:

<script src="test.js?rndstr=<%= getRandomStr() %>"></script>

More info on cache-busting can be found here:

https://www.curtiscode.dev/post/front-end-dev/what-is-cache-busting

You can append a queryString to your src and change it only when you will release an updated version:

<script src="test.js?v=1"></script>

In this way the browser will use the cached version until a new version will be specified (v=2, v=3...)