source: trip-planner-front/src/app/auth/auth.interceptor.ts

import { HttpHandler, HttpHeaders, HttpInterceptor, HttpRequest } from "@angular/common/http";
import { Injectable } from "@angular/core";

@Injectable({
  providedIn: "root"
})
export class AuthInterceptor implements HttpInterceptor {

  constructor() { }

  intercept(req: HttpRequest<any>, next: HttpHandler) {

    if (sessionStorage.getItem('username') && sessionStorage.getItem('token')) {
      req = req.clone({
        headers: req.headers.set("Authorization", "" + sessionStorage.getItem("token"))
      });
    }

    return next.handle(req);

  }
}