Universally Speaking
Hi, I'm Craig
This is a deep dive!
@phenomnominal 2019
Assumptions:
You know some Angular ✅
You've heard of Angular Universal ✅
What we're covering:
How does Angular Universal work?
What problems does it solve?
How do we make our applications work with Universal?
Why would you not want to use Universal?
@phenomnominal 2019
🌟
🌟
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🌟
🌟
🌟
How does Angular Universal work?
@phenomnominal 2019
Angular
my-site.nz/item/:id
<html>
<link
rel="stylesheet"
href="/static/styles.css">
<script
src="/static/script.js">
<body>
<trade-me>
<div
class="my-loading">
</div>
</trade-me>
</body>
</html>
rel="stylesheet"
href="/static/styles.css"
src="/static/script.js"
class="my-loading"
"stylesheet"
"/static/styles.css"
"/static/script.js"
"my-loading"
Generic application loading state
Static resources
@phenomnominal 2019
Angular
my-site.nz/static/script.js
my-site.nz/static/styles.css
function () {
...
}
html {
...
}
() {
...
}
{
...
}
...
...
@phenomnominal 2019
Angular
my-site.nz/api/item/:id.json
{"id":"1234567890", ... }
@phenomnominal 2019
Can we remove some of those round trips?
@phenomnominal 2019
Angular Universal
my-site.nz/item/:id
<html>
<link
rel="stylesheet"
href="/static/styles.css">
<script
src="/static/script.js">
<body>
<my-site>
<my-site-homepage>
<my-site-search>
</my-site-homepage>
</my-site>
</body>
<script
id="server-app-state">
</script>
</html>
rel="stylesheet"
href="/static/styles.css"
src="/static/script.js"
id=
"stylesheet"
"/static/styles.css"
"/static/script.js"
"server-app-state"
Real application content!
Inlined server request data
@phenomnominal 2019
@phenomnominal 2019
What problems does it solve?
Performance
Slower "Time to First Byte" due to server processing time
Faster "First Paint" over client-only application, particularly for mobile devices
This can be mitigated with caching - both on the server & on the client with a service worker
Slower "Time to Interactive" due to client-side rehydration
Faster discovery of resources required for your application
Measure, experiment, and find what works for your app
@phenomnominal 2019
SEO/No JS Environments
Some crawlers have JavaScript capabilities, but who knows how that really works (not me!)
Support for browsers with JavaScript disabled, or old engines.
(Check out Igor Minar's talk from ng-conf 2018 for how angular.io handles SEO without Angular Univeral)
If you're competing against other websites, server rendering can give you an advantage over client-only SEO
@phenomnominal 2019
Social links
Pre-rendered content for Facebook, Twitter, etc.
@phenomnominal 2019
🚀
🇳🇿
🌎
🦄
⭐️
Neat.
🛰
⭐️
⭐️
⭐️
⭐️
⭐️
⭐️
⭐️
⭐️
🆖
🛸
@phenomnominal 2019
How do we make Angular Universal work with our applications?
@phenomnominal 2019
🤔
@phenomnominal 2019
@phenomnominal 2019
Asteroids!
Facts about asteroids:
Categorised as "minor planets"
Not comets or meteoroids
14,464 known "near-Earth" asteroids
ALLEGEDLY killed the dinosaurs
Cool names like "Odysseus" and "James Bond"
💥
💥
💥
💥
💥
💥
💥
💥
@phenomnominal 2019
Asterank
@phenomnominal 2019
We can rebuild it
@phenomnominal 2019
Angular CLI
@phenomnominal 2019
ng new universally-speaking && cd universally-speaking
ng add @nguniversal/express-engine --clientProject universally-speaking
npm run build:ssr
npm run serve:ssr
Demo.
@phenomnominal 2019
@phenomnominal
2018
⭐️ A new app Angular CLI app
⭐️ Build steps for two different versions of the app and the server
⭐️ All the necessary Angular Universal dependencies
🎉🎉🎉🎉🎉
⭐️ A new server.ts file which contains the server code
⭐️ A modified app.module.ts that uses withServerTransition
⭐️ A new app.server.module.ts file for the server application
⭐️ A modified main.ts that waits for DOMContentLoaded before bootstrap
⭐️ A new main.server.ts file for the server bootstrap
What do we have?
@phenomnominal 2019
JavaScript runtime (no DOM)
Driven by Chrome's V8 engine
Use everyone else's code via
@phenomnominal 2019
Node.js
Require the built Universal app
Set up the engine for running the application
Pass all requests to the engine
Create the Express server
Start the server
@phenomnominal 2019
const app = express();
const { AppServerModuleNgFactory, LAZY_MODULE_MAP } = require('./dist/server/main');
app.engine('html', ngExpressEngine({
bootstrap: AppServerModuleNgFactory,
providers: [
provideModuleMap(LAZY_MODULE_MAP)
]
}));
app.get('*', (req, res) => {
res.render('index', { req });
});
app.listen(PORT, () => {
console.log(`Node Express server listening on http://localhost:${PORT}`);
});
Time passing
@phenomnominal 2019
@phenomnominal 2019
Demo.
@phenomnominal
2018
What do we have?
⭐️ @angular/cli application
⭐️ Asteroid data requested from Asterank
⭐️ WebGL animation
⭐️ @ngrx/store + router-state + entity
😔 Client render only
@phenomnominal 2019
window is not defined
@phenomnominal 2019
How do we run this on the server?
🤔
@phenomnominal 2019
Angular Universal
Run your Angular application anywhere...
https://www.youtube.com/watch?v=_trUBHaUAR0
@phenomnominal 2019
Anywhere...
@phenomnominal 2019
@angular/platform-browser
@angular/platform-browser-dynamic
@angular/platform-server
@angular/platform-webworker // Gone!!
@angular/platform-webworker-dynamic // Gone!!
@angular/platform-terminal // !!!
How do we run this anywhere?
🤔
@phenomnominal 2019
One implementation for all environments
One implementation for a specific environment
Different implementations for each environment
Different functionality for each environment
@phenomnominal 2019
Different implementations for each environment
@phenomnominal 2019
Platform-specific modules
Remember app.module.ts & app.server.module.ts?
@phenomnominal 2019
// app.module.ts
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { RouterModule } from '@angular/router';
import { AppComponent } from './app.component';
@NgModule({
bootstrap: [AppComponent],
declarations: [AppComponent],
imports: [
BrowserModule.withServerTransition({ appId: 'serverApp' }),
RouterModule.forRoot([{
// Routes...
}], {
initialNavigation: 'enabled'
})
]
})
export class AppModule { }
// app.server.module.ts
import { NgModule } from '@angular/core';
import { ServerModule } from '@angular/platform-server';
import { ModuleMapLoaderModule } from '@nguniversal/module-map-ngfactory-loader';
import { AppModule } from './app.module';
import { AppComponent } from './app.component';
@NgModule({
bootstrap: [AppComponent],
imports: [
AppModule,
ModuleMapLoaderModule,
ServerModule
]
})
export class AppServerModule { }
Services
Provide different implementations for different environments:
Server implementation for Renderer
Server implementation for HttpClient
@phenomnominal 2019
// @angular/platform-server
@NgModule({
exports: [BrowserModule],
imports: [HttpModule, HttpClientModule, NoopAnimationsModule],
providers: [
SERVER_RENDER_PROVIDERS,
SERVER_HTTP_PROVIDERS,
// ...
]
})
export class ServerModule { }
One implementation for all environments
@phenomnominal 2019
Avoiding the DOM
Do not use the DOM directly! There's almost always a way to do the same thing with Angular's abstractions.
@phenomnominal 2019
Components
@Input, @Output, @HostBinding, @ViewChild, @ContentChild, ngStyle, ngClass.
You may occasionally need to reach for the Renderer:
Normal dependency injection
@phenomnominal 2019
import { Component, Renderer2 } from '@angular/core'
@Component({
// ...
})
export class MyComponent {
constructor (
private _renderer: Renderer2
) { }
}
But what if you have to use the DOM?
🤔
@phenomnominal 2019
Be explicit about it
Be defensive!
Explicit null type is good
Only run code if window is available.
@phenomnominal 2019
@Injectable({
providedIn: 'root'
})
export class WindowRef<T extends Window = Window> {
private readonly _window: T | null;
constructor () {
this._window = this._getWindow();
}
public useWindow <U> (handler: (window: T) => U): U | null {
return this._window ? handler(this._window): null;
}
public _getWindow (): T | null {
return typeof window !== 'undefined' ? window as T : null;
}
}
Provide an alternative
Use custom services to abstract around DOM APIs.
Only fall back to the actual DOM if you have to
Optional injection token!
Use the optionally injected value if available
@phenomnominal 2019
export const URL_LOCATION_TOKEN = new InjectionToken('URL_LOCATION');
@Injectable({
// ...
})
export class UrlLocationService {
constructor (
private _window: WindowRef,
@Optional() @Inject(URL_LOCATION_TOKEN) private _location: Location
) {
this._location = this._location || this._window.useWindow(w => w.location);
}
public getHostname (): string {
return this._location.hostname;
}
}
Hack it?
Some third-party code won't want to play nicely...
(here's lookin' at you three-trackballcontrols 😅)
Set up globals
Require troublesome module
Clean up after
Directly check for window
@phenomnominal 2019
if (typeof window === 'undefined') {
(global as any).window = {};
require('three-trackballcontrols');
delete (global as any).window;
}
Check the platform...
@phenomnominal 2019
Check the platform
If you really must...
Injectable PLATFORM_ID token
Use the method for the specific platform
@phenomnominal 2019
import { isPlatformBrowser, isPlatformServer } from '@angular/common';
import { Inject, PLATFORM_ID } from '@angular/core';
@Component({
// ...
})
export class MyComponent {
constructor (
@Inject(PLATFORM_ID) private _platformId: Object
) { }
public myExpensiveDomHeavyOperation (): void {
if (!isPlatformBrowser(this._platformId) {
return;
}
this._useTheDom();
}
}
@phenomnominal 2019
Demo.
@phenomnominal
2018
document is not defined
One implementation for a specific environment
@phenomnominal 2019
Just turn it off
Add @Optional injection annotation
Trusty if statement
Check for the presence of an injected service:
@phenomnominal 2019
@Component({
selector: 'us-asteroid-visualisation',
templateUrl: './asteroid-visualisation.component.html',
styleUrls: ['./asteroid-visualisation.component.scss'],
changeDetection: ChangeDetectionStrategy.OnPush
})
export class AsteroidVisualisationComponent implements OnInit {
@ViewChild('container') public container: ElementRef;
constructor (
private _asteroidDataFacade: AsteroidDataFacade,
private _renderer: Renderer2,
@Optional() private _visualisationService: VisualisationService
) { }
public ngOnInit (): void {
if (this._visualiationService) {
const canvas = this.visualisationService.init(this.container);
this._renderer.appendChild(this.container.nativeElement, canvas);
}
}
}
Just turn it off
Turn things off at a provider level:
Provide null for specific platform
Corresponding injection token
@phenomnominal 2019
@NgModule({
imports: [
// ...
],
bootstrap: [AppComponent],
providers: [
{ provide: VisualisationService, useValue: null }
]
})
export class AppServerModule { }
@phenomnominal 2019
Demo.
Different functionality for each environment
@phenomnominal 2019
State Transfer
The whole application runs twice.
This means duplicate API calls! 🤯
This call happens twice
@phenomnominal 2019
import { Component, OnInit } from '@angular/core';
import { HttpClient } from '@angular/common/http';
@Component({
// ...
})
export class AppComponent implements OnInit {
asteroids: Array<Asteroid>;
constructor (
private _asteroidDataService: AsteroidDataService
) { }
public ngOnInit (): void {
this._asteroidDataService.getAsteroids().subscribe(data => this.asteroids = data);
}
}
State Transfer
Inject TransferState
Create a state key
Set the state on the first run
Re-use it if it's available
@phenomnominal 2019
import { TransferState, makeStateKey } from '@angular/platform-browser';
const ASTEROIDS = makeStateKey('asteroids');
@Component({ ... })
export class AppComponent implements OnInit {
public asteroids = Array<Asteroid>;
constructor (
private _asteroidDataService: AsteroidDataService,
private _transferState: TransferState
) { }
public ngOnInit (): void {
this.asteroids = this._transferState.get(ASTEROIDS, null);
if (!this.asteroids) {
this._asteroidDataService.getAsteroids()
.subscribe(data => {
this.asteroids = data;
this._transferState.set(ASTEROIDS, data);
});
}
}
}
State Transfer
The state transfer data is inlined into the HTML response as a blob of JSON. This means...
Don't send too much data!
Your whole state must be JSON serialisable!
@phenomnominal 2019
State Transfer + Store
@phenomnominal 2019
@Injectable()
export class AsteroidDataEffects {
// ...
@Effect()
public getAsteroidDataFromApiEffect$ = this._actions$.pipe(
ofType<GetAsteroidDataFromApiAction>(GetAsteroidDataFromApiAction.TYPE),
switchMap(action => {
return this._asteroidDataService.getAsteroidData(action.options).pipe(
map(
response =>
new GetAsteroidDataFromApiSuccessAction(action.options, response)
),
catchError(
err =>
of(new GetAsteroidDataFromApiFailAction(action.options, err))
)
);
})
);
}
Using a centralised data store makes this even more interesting:
When a Get action happens
Call through to the API
State Transfer + Store
@phenomnominal 2019
If you're using a central data store to manage your application state, you can just transfer the whole store!
State Transfer + Store
One state key for your whole store
Read the whole store and serialise
@phenomnominal 2019
@NgModule({
imports: [BrowserTransferStateModule]
})
export class ServerStateModule {
constructor (
private _transferState: TransferState,
private _store: Store<State>
) {
this._transferState.onSerialize(STATE_KEY, () => {
let stateToTransfer = null;
this._store.pipe(
select(state => state),
take(1)
).subscribe(state => stateToTransfer = state);
return stateToTransfer;
});
}
}
Specific NgModule for the server app
State Transfer + Store
Use the same key on the client
Dispatch a new action with the whole serialised store
@phenomnominal 2019
@NgModule({
imports: [BrowserTransferStateModule]
})
export class ClientStateModule {
constructor (
private _transferState: TransferState,
private _store: Store<State>
) {
if (this._transferState.hasKey(STATE_KEY)) {
const state = this._transferState.get<State>(STATE_KEY, {});
this._trasferState.remove(STATE_KEY);
this._store.dispatch(new TransferStateAction(state));
}
}
}
Specific NgModule for the client app
State Transfer + Store
@phenomnominal 2019
@Injectable()
export class AsteroidDataEffects {
// ...
@Effect()
public getAsteroidDataFromApiEffect$ = this._actions$.pipe(
ofType<GetAsteroidDataFromApiAction>(GetAsteroidDataFromApiAction.TYPE),
switchMap(action => {
return this._asteroidDataService.getAsteroidData(action.options).pipe(
map(
response =>
new GetAsteroidDataFromApiSuccessAction(action.options, response)
),
catchError(
err =>
of(new GetAsteroidDataFromApiFailAction(action.options, err))
)
);
})
);
}
Let's quickly look at our Effect again:
State Transfer + Store
@phenomnominal 2019
@Effect()
public getAsteroidDataEffect$ = this._actions$.pipe(
ofType<GetAsteroidDataFromApiAction>(GetAsteroidDataAction.TYPE),
switchMap(action => {
this._store.select(AsteroidDataSelectors.currentAsteroidData).pipe(
take(1),
map(() => new GetAsteroidDataFromApi(action.options))
)
})
)
@Effect()
public getAsteroidDataFromApiEffect$ = this._actions$.pipe(
ofType<GetAsteroidDataFromApiAction>(GetAsteroidDataFromApiAction.TYPE),
switchMap(action => {
return this._asteroidDataService.getAsteroidData(action.options).pipe(
map(response =>
new GetAsteroidDataFromApiSuccessAction(action.options, response)
)
);
})
);
We can split this in two:
State Transfer + Store
Use a simple cache layer to prevent duplicated calls
Mark each API response with a cache time
Only do the call if the cache time has expired
@phenomnominal 2019
@Effect()
public getAsteroidDataEffect$ = this._actions$.pipe(
ofType<GetAsteroidDataFromApiAction>(GetAsteroidDataAction.TYPE),
switchMap(action => {
this._store.select(AsteroidDataSelectors.currentAsteroidData).pipe(
take(1),
filter(item => this._cacheService.shouldFetch(item, TWO_MINUTES)),
map(() => new GetAsteroidDataFromApi(action.options))
)
})
)
@Effect()
public getAsteroidDataFromApiEffect$ = this._actions$.pipe(
ofType<GetAsteroidDataFromApiAction>(GetAsteroidDataFromApiAction.TYPE),
switchMap(action => {
return this._asteroidDataService.getAsteroidData(action.options).pipe(
map(response =>
new GetAsteroidDataFromApiSuccessAction(action.options, response, Date.now())
)
);
})
);
@phenomnominal 2019
Demo.
One implementation for all environments
One implementation for a specific environment
Different implementations for each environment
Different functionality for each environment
@phenomnominal 2019
Cool.
@phenomnominal 2019
Why wouldn't you use Angular Universal?
🤔
@phenomnominal 2019
Performance
Universal is not a magical silver rocket.
If performance is your only goal, just ship less JavaScript
Rocket Lab! (YEAH NZ 🇳🇿)
It can definitely make things worse if you're not careful!
@phenomnominal 2019
Complexity
You now need a "real" server, not just static files.
Harder to get working, harder mental model, harder to get people shipping value
There will be lots more code - logging, monitoring
@phenomnominal 2019
Workflow/DX
It's very slow...
Bazel will fix it?
@phenomnominal 2019
So it's just a dumpster fire?
@phenomnominal 2019
@phenomnominal 2019
Should I use Angular Universal?
If you want/need your Angular app to be crawled by Search Engines
@phenomnominal 2019
If you want/need improved No JS/old browser support
@phenomnominal 2019
If you want/need content previews for Social Media
@phenomnominal 2019
AND if you're willing to fight for better perceived performance
@phenomnominal 2019
Angular Universal
@phenomnominal 2019
Chur.
@phenomnominal 2019
Universally Speaking
By Craig Spence
Universally Speaking
Craig Spence - ComponentsConf 2019 - Universally Speaking
- 3,106