Most developers think of <script type="module"> as way to load ES modules (and of course this is true), but <script type="module"> also has a more immediate and practical use-case—loading regular JavaScript files with ES2015+ features and knowing the browser can handle it!

To put that another way, every browser that supports <script type="module"> also supports most of the ES2015+ features you know and love.

This very helpful article outlines how you can take advantage of modern JavaScript features while still serving usable code to older browsers.