This is the
qwebchannel.js file exactly as it is from the Qt WebChannel repository, uploaded to NPM for convenience.
Note: not an official Digia upload, this is a community-maintained package
You can take the JS file and use it in the browser with a
<script /> tag or via Browserify/Webpack, or from node using
require('qwebchannel'). From this, you can interact your Qt 5 or PySide 2-based application from a WebEngine view or a Node script.
Assorted links/reading material: