GitHub Action Node JS Tutorial Required

Is there any tutorial for Node JS for GitHub Action? For example, what are the methods and properties exposed by core package? Also, is there a necessity that the file name must be index.js? None of these things seem to be documented properly. Can anyone please help?

This is the official guide for JavaScript Actions:

It links to the core package which has a readme about its features: toolkit/packages/core at main · actions/toolkit · GitHub

The entry point for an Action can be specified in the runs.main key as described here: