Easy to understand HTML + JS code, which displays weather radar (past and future) and infrared satellite tiles on the map. The main using the Leaflet.js library with OpenStreetMap as a base map solution. Version for Google Maps and MapBox GL JS also available in a separate files.
Check it in your browser: rainviewer-api-example.html
For MapBox and Google Maps, you need to use a pretty similar code, but you need to put your API key in that examples to display the base map. Search for YOUR_API_KEY_HERE in the source code and replace it with your own key. These files will not display the map until you put your API KEY in it.