Angular Intercaptors

auth.interceptors.ts

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

import { AuthService } from '../auth/auth.service';

@Injectable()
export class AuthInterceptor implements HttpInterceptor {
  constructor(private authService: AuthService) {}

  intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    console.log('Intercepted!', req);
    // const copiedReq = req.clone({headers: req.headers.set('', '')});
    const copiedReq = req.clone({params: req.params.set('auth', this.authService.getToken())});
    return next.handle(copiedReq);
    // return null;
  }
}

core.module.ts

import { NgModule } from '@angular/core';
import { HTTP_INTERCEPTORS } from '@angular/common/http';


import { AuthInterceptor } from '../shared/auth.interceptor';
import { LoggingInterceptor } from '../shared/logging.interceptor';

@NgModule({
  declarations: [
    HeaderComponent,
    HomeComponent
  ],
  imports: [
    SharedModule,
    AppRoutingModule
  ],
  exports: [
    AppRoutingModule,
    HeaderComponent
  ],
  providers: [    
    AuthService,
    {provide: HTTP_INTERCEPTORS, useClass: AuthInterceptor, multi: true},
    {provide: HTTP_INTERCEPTORS, useClass: LoggingInterceptor, multi: true}
  ]
})
export class CoreModule {}

logging.interceptor.ts

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

export class LoggingInterceptor implements HttpInterceptor {
  intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    return next.handle(req).pipe(tap(
      event => {
        console.log('Logging interceptor', event);
      }
    )
    )
  }
}