Discussion on: Steps for upgrading AngularJS to hybrid Angular 9

Tips for migrating AngularJS to Angular 9:

• Never ever reference Angular code from AngularJS and vice versa. Otherwise the bundling process will not work properly and ends with big fat bundles which bootstraps slow.
• Use lazy loading in Angular
• Don't use a vendor bundle since Angular knows how to split the bundles efficiently
• Big bundles / slow bootstrapping? Use webpack bundle analyzer to analyze the bundle
• Shared types? Use a *.d.ts file

@psamim :
You should remove
import { angularJsModule } from "../ajs/app";

and use this instead (directly in ngDoBootstrap):

import('../ajs/app').then((angularJsModule) => {
    // do the bootstrapping stuff here
});

This enables lazy loading and splits the AngularJS in a separate bundle.