http interceptor angular

app.module.ts

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';

import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';

import { HttpClientModule }    from '@angular/common/http';

// for token interceptor 
import { HTTP_INTERCEPTORS } from '@angular/common/http';
import { TokenInterceptor } from '../app/core/interceptors/token.interceptor';

// components
import { HomeComponent } from './components/home/home.component';
import { UsersComponent } from './components/users/users.component';

@NgModule({
  declarations: [
    AppComponent,
    HomeComponent,
    UsersComponent
  ],
  imports: [
    BrowserModule,
    AppRoutingModule,
    HttpClientModule,
  ],
  providers: [
    {
      provide: HTTP_INTERCEPTORS,
      useClass: TokenInterceptor,
      multi: true
    }
  ],
  bootstrap: [AppComponent]
})
export class AppModule { }

token.interceptor.ts

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

import {
  HttpRequest,
  HttpHandler,
  HttpEvent,
  HttpInterceptor
} from '@angular/common/http';

import { Observable } from 'rxjs';

import { ConfigService } from '../http/config/config.service';

@Injectable()
export class TokenInterceptor implements HttpInterceptor {

  constructor(
    private config: ConfigService
  ) {}

  intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    
    request = request.clone({
      setHeaders: {
        Authorization: `Bearer ${this.config.getToken()}`
      }
    });

    console.log("Sending request with new header now ... INTERCEPTED");

    return next.handle(request);
  }

}