Angular : How declare variable at Module and access it from all component?

Question

I want to declare variable in my app.module and access it from children components
without declare it again or use global injection.

Is this possible?

Answer 1

You can define a String Token and inject it at your component via Injector from @angular/core.

App.module.ts

const testVar = 'some value';
@NgModule({
  ...
  providers: [
    { provide: 'A', useValue: testVar}   // define a string token
  ]
})
export class AppModule { }

Component

import { Injector } from '@angular/core';

constructor(private injector: Injector) {
  const A = this.injector.get('A');
  console.log(A);
}

DEMO