ESRI Javascript API 4 with Angular 2 - Transition to Webpack

Since my first post on Angular 2 and the ESRI API, I’ve transitioned from SystemJS to Webpack which I’m enjoying thoroughly.

Sample App w/ Webpack setup:

IMO, Webpack has a few major advantages over SystemJS:

  • Development build step is much faster and lite-server does not bog down with memory leaks (not sure why that happened with the SystemJS setup but lite-server got slower and slower until restarted).
  • Webpack takes care of bundling code for you (everything expect the ESRI requires).
    • This setup also bundles each components’ html and css in the main bundle.
  • Feels like less of a hack to use with esri - simply require in each module and that’s it. Setup is simply specifying ESRI as an “external”. Nothing really special there and it just works.
  • No need for a grunt/gulp step to minimize, etc. Webpack is pretty comprehensive.

This app is just a map with a custom coordinate display component (bottom left):

Coordinate component

I’ve used a similar webpack configuration to this in a couple production apps over the last several months. Unit testing w/ this setup and Typescript is finally starting to feel natural (instead of a large very verbose burden w/ es5). I’ve found it fairly straightfoward to test domain classes and models w/ business logic where I feel you get the most bang for your buck from testing. What I haven’t quite figured out yet is how to test components (and when it’s actually worth the effort). This project contains a working test for the coordinate component… It works, but I’m not yet convinced it’s the best way to go about it. Please comment if you have experience here!

Coordinate Component test:

import { TestBed, ComponentFixture } from '@angular/core/testing';
import { DebugElement } from '@angular/core';

import { CoordinateComponent } from './coordinate.component';

let fixture: ComponentFixture<CoordinateComponent>;
let component: CoordinateComponent;
let de: DebugElement;
let el: HTMLElement;
let $mapDiv;
let mapDivEl: Element;
beforeEach(() => {
  // refine the test module by declaring the test component
    declarations: [CoordinateComponent]

  // create component and test fixture
  fixture = TestBed.createComponent(CoordinateComponent);
  el = fixture.nativeElement;

  // get test component from the fixture
  component = fixture.componentInstance;

  // add a div to the body
  $mapDiv = $('<div>', { id: 'mapDiv' }).appendTo('body');
  mapDivEl = $mapDiv[0];

  // mock required MapView props/functions
  component.mapView = <any>{
    container: mapDivEl,
    toMap: (point) => {
      return {
        longitude: 5,
        latitude: 10
    zoom: 7,
    scale: 500

  // runs ngOnInit

describe('Coordinate', () => {
  it('should update lat/long on mousemove', () => {
    mapDivEl.dispatchEvent(new Event('mousemove', {
      bubbles: true,
      cancelable: true
    // pageX, pageY
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