Angular Universal

Rendering JavaScript on the Server

@MarkPieszak

Hey! I'm Mark Pieszak

* Founder of  http:// DevHelp.Online
   Development / Consulting / Training Firm


   - Helping teams and companies achieve their
     Angular / JavaScript / ASP.NET goals.

 

* Angular Universal team

 -
Working on improving Universal
   & Angular-CLI & ASP.NET integration

Who is this guy?

Mark

Pie

Zack

Szak

Check us out online!
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@MarkPieszak

 

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@MarkPieszak

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@MarkPieszak
 

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Story
Time...

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Make sure to push 

to not miss any Slides !

Brief History of the Web

Server-side
Rendered
Websites

The Server-Side

Rendered Web

(Which has improved immensely
since the following screenshots of course!)

aka: SSR

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The old Web

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The old Web

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The old Web

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Some things change...
Others stay the same

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What does SSR get Right?

Search Engine Optimization

  - Since everything was Server-rendered,
    SEO was never an "issue"...
   
  - It was just something you
    had to add in your code

Great for Static sites

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Many other things...

Where does SSR lack sometimes?

Overall "User-Experience"

  - Full page-loads were needed to show new content
    or during any user interaction

  - More server requests because of this

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What did the Web do next?

Brief History of the Web

Server-side
Rendered
Websites

Single Page Applications

Single Page Applications

aka: Client-side rendering

( CSR )

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More or less...

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What does CSR get Right?

A great fully interactive & rich user experience

 

Quick page transitions

Great for web applications

Overall we get that nice
"Perception"
that things are -happening-

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Where does CSR fall short?

No Search-engine optimization (at least not easily)

 

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Where does CSR fall short?

Longer initial load time

  - Waiting for assets to download

  - Code needs to run

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Where do we go from here?

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SSR

CSR

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SSR

CSR

SEO ✔
Faster initial paint
Social Media Link Previews
Great user experience
Fully interactive

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Can we get the best of both worlds?

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SSR

CSR

The Birth of
"Isomorphic"
JavaScript

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Brief History of the Web

Server-side
Rendered
Websites

Single Page Applications

"Isomorphic" JavaScript

What is Isomorphic JavaScript?

JavaScript
Application
<code />

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Same JavaScript Code running
on the Server

Same JavaScript Code running
on the Browser

This was me...

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Serialize the application
to a String "<html><head>..."

Your Applications JS code gets downloaded and begins to Bootstrap

( In the background ...)

JavaScript
Application
<code />

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serve it to the browser

Application finishes bootstrapping

Now we have a
- fully functioning -
Single Page Application

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Angular Universal

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Community-driven project originally
Originally created by:

Patrick Stapleton (PatrickJS)
Co-Founder of OneSpeed.io

Jeff Whelpley
CTO GetHuman

Rest of the Universal Team:

Mark Pieszak (me)
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Jason Jean
Forbes

Jeff Cross
Nrwl.io

Wassim Chegham
SFEIR

Alex Rickabaugh
Angular Core Team

Vikram Subramanian
Angular Core Team

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Moved from a separate repo to
inside Angular Core in 2017

Angular Universal

@angular/
platform-server

renderModuleFactory()

Angular Code bundles
"Bootstraps"
platformBrowser()

( In the background ...)

Angular
Application
<code />

Node Server

App to a String

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Angular
Application
<code />

When it finishes Bootstrapping, it replaces existing HTML "App" with Client-side rendered SPA version.


Boom! We have a normal Angular application

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Angular-CLI Integration

git clone http://www.github.com/angular/universal-starter

cd universal-starter

npm i 
// or yarn install

// To run Dynamic universal rendering
npm run build:ssr && npm run serve:ssr
// Open localhost:4000

// To run Static "prerendering"
npm run build:prerender && npm run serve:prerender
// Open http://127.0.0.1:8080

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- Start Here -
Working Example

http://www.github.com/angular/universal-starter

Angular-CLI Integration

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Have an existing CLI Application
you want to make Universal?

 

https://github.com/angular/angular-cli/wiki/stories-universal-rendering

Read the CLI Wiki story on Universal

How does Universal work?

Essentially lots of Dependency Injection

Possible because of Angular's

Compiler & Renderer not being tied to the Browser.

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How does Universal work?

Dependency Injection Mania

Provide Use
RenderFactory2 ServerRenderFactory2
BrowserXHR ServerXHR (Zone wrapped)
DOCUMENT Domino
PlatformLocation ServerPlatformLocation
StylesHost ServerStylesHost

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Use these instead

How does Universal work?

Angular App

main.ts

main.server.ts

platformBrowser()

platformServer()

app.module.ts

app.server.module.ts

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How does Universal work?

Angular App

BrowserModule

imports AppModule

imports ServerModule

app.module.ts

app.server.module.ts

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How does Universal work?

@NgModule({
  exports: [BrowserModule],
  imports: [HttpModule, HttpClientModule, NoopAnimationsModule],
  providers: [
    SERVER_RENDER_PROVIDERS,
    SERVER_HTTP_PROVIDERS,
    {provide: Testability, useValue: null},
  ],
})

export class ServerModule { } // <--

ServerModule imports all the Dependency Injection -magic-

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Static vs Dynamic Rendering?

Static prerendering is done at BUILD-time
  - Great for Static sites
  - Each route will have its content pre-rendered into an .html

     file

  - Simply `serve` up the dist/browser folder to your server.

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/ dist /

    / browser / 
    
        index.html
        about.html
        contactus.html
        // ... etc ...  

Static vs Dynamic Rendering?

Dynamic SSR is done at RUN-time
  - This is more typical, dynamic sites where data is Http based

     and data is constantly changing.
  - Each route will render at run-time when requested and is            served to the client.    

  - You must deploy the Node server

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/ dist /

    / browser /
        index.html
        // static assets
 
    / server / 
        // our server "universal" bundle, etc...

    // ** Our Node Express server we need to fire up **
    server.js

Node server time

import { AppServerModuleNgFactory } from './PATH/TO/server.bundle';
import { renderModuleFactory } from '@angular/platform-server';
import * from 'fs';

// Express server
const app = express();

app.get('*', (req, res) => {

    renderModuleFactory(AppServerModuleNgFactory, {
        extraProviders: [
            {
                provide: INITIAL_CONFIG,
                useValue: {
                  document: fs.readFileSync('dist/browser/index.html').toString(),
                  url: req.originalUrl
                }
            },
            // other providers you want to pass in
        ]
    }).then(html => {
        res.send(html);

    }).catch(error => { // errors });
});

app.listen(4000, () => {
  console.log(`Node Express server listening on http://localhost:${PORT}`);
});

This is NOT a working example - just conceptual

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For every Request

Serialize our Angular AoT'd Angular NgModule

Our index.html

Current URL

Send the resulting <html>
to the Browser!

Node server time

You can use renderModuleFactory() manually,
but I'd recommend just using the expressEngine.

http://www.github.com/angular/universal

Additional Universal libraries found in the npm namespace @nguniversal

 

More add-ons, coming soon!

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@nguniversal express-engine


import { ngExpressEngine } from '@nguniversal/express-engine';
import { provideModuleMap } from '@nguniversal/module-map-ngfactory-loader';

// Our Universal express-engine (github.com/angular/universal)
app.engine('html', ngExpressEngine({
    bootstrap: AppServerModuleNgFactory,
    providers: [
        provideModuleMap(LAZY_MODULE_MAP)
    ]
}));

app.set('view engine', 'html');

app.get('*', (req: Request, res: Response) => {
  res.render('index', {
    req,
    res
  });
});

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Notice Request/Response are passed in to the Engine which handles creating the InjectionTokens and passes them into Angular,
now you can use them within your Angular App!

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

import { Request, Response } from 'express';
import { REQUEST, RESPONSE } from '@nguniversal/express-engine/tokens'; // <--

export SomeComponent {

    private request: Request;
    private response: Response;

    constructor(
        private injector: Injector
    ) { 
        this.request = this.injector.get(REQUEST);
        this.response = this.injector.get(RESPONSE);

        // cookies / headers / anything from our original Node Request
        // same with Response
    }
}

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Request/Response inside your Angular App

@nguniversal express-engine

Grab the Request/Response using the Injector

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Common SSR Gotchas

Server-side Render

Client-side Render

A

B

C

A

B

C

Renders entire App

Renders entire App
Again

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Common SSR Gotchas

Server-side Render

Client-side Render

A

B

C

A

B

C

Http call made here

Http call will be triggered -again-

Template "flickers" when Data goes blank then re-appears

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Common SSR Gotchas

Server-side Render

Client-side Render

A

B

C

A

B

C

Component "B" uses
"window" or "document"

"window/document" exists in the Browser-world

How does Node handle it?

Throws error, server stops.

No Bueno...

How can we handle these common SSR issues in our Angular Universal Apps?

New to Angular 5.0

- Upcoming in Angular 5.0 is the new TransferState

  - Use this so Http calls don't get hit TWICE
    Once during SSR, and again during CSR.

- Use TransferHttpCacheModule to have all GET HttpClient requests automatically transferred and re-used!

import { BrowserTransferStateModule } from '@angular/platform-browser';
import { TransferHttpCacheModule } from '@nguniversal/common';

imports: [
  // ...
  HttpClientModule,
  TransferHttpCacheModule, // <-- automatically caches HttpClient GET requests
  BrowserTransferStateModule // <--
]

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import { ServerTransferStateModule } from '@angular/platform-server';
imports: [ 
  // ... 
  ServerTransferStateModule // <--
]

Browser (app.module.ts)

Server (app.server.module.ts)

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Now with HttpTransferCache

Server-side Render

Client-side Render

A

B

C

A

B

C

Http call made here

Http call re-used

Data sent down with html and re-used
when CSR calls the same Http call

Other Universal "Gotchas"

- Never touch the "window"
     - If you must, create a WindowService and use
       Depenency Injection to provide different versions 

@Injectable()
export class WindowService {
  // Some typical window use-cases
  public navigator: any = {};
  public location: any = {};
  public alert(msg: string) { return; }
  public confirm(msg: string) { return; }
  public setTimeout(handler: (...args: any[]) => void, timeout?: number): number { return 0; }
  public clearTimeout(timeoutId: number): void { }
  public setInterval(handler: (...args: any[]) => void, ms?: number, ...args: any[]): number { return 0; }
  public clearInterval(intervalId: number): void { }
  public ga(command: string | Function, params?: any, extra?: any): void { }
  // ...
}

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export function win () {
  return typeof window !== 'undefined' ? window : {};
}

// NgModule providers[]
{ 
   provide: WindowService, 
   useFactory: (win) // ^ above
} 
// app.server.module.ts NgModule providers[]
{ provide: WindowService, useClass: WindowService }, 

Browser (app.module.ts)

Server (app.server.module.ts)

Other Universal "Gotchas"

- Never touch the "window"
     - Also, try to wrap these things and ONLY do them if you're in           the Browser Platform.              

import { OnInit, PLATFORM_ID } from '@angular/core';
import { isPlatformBrowser, isPlatformServer } from '@angular/common';

export class SomeComponent implements OnInit {

  private isBrowser: boolean = isPlatformBrowser(this.platformId);

  constructor(
    private window: WindowService,
    @Inject(PLATFORM_ID) private platformId: Object
  ) { }

  ngOnInit() {

    if (this.isBrowser) { 
      (<any>this.windowService).$('body')... // something crazy involving the window
    }

  }
}

Protip: Use isPlatformBrowser() as much as possible!

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Other Universal "Gotchas"

- If you -must- use document, grab it from platform-browser


import { DOCUMENT } from '@angular/common';

constructor(@Inject(DOCUMENT) private document) { 
  this.document.querySelector('#test') // do something
}

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Using Window/Document

Server-side Render

Client-side Render

A

B

C

A

B

C

Component "B" uses
"window" or "document"

"window/document" exists in the Browser-world

Because of Dependency Injection, window never used.

Node keeps running

Other Universal "Gotchas"

- Be careful with setTimeout & setInterval

 

import { PLATFORM_ID } from '@angular/core';
import { isPlatformBrowser, isPlatformServer } from '@angular/common';

export class SomeComponent {

  private isBrowser: boolean = isPlatformBrowser(this.platformId);

  constructor(
    private window: WindowService,
    @Inject(PLATFORM_ID) private platformId: Object
  ) { }

  ngOnInit() {
    if (this.isBrowser) { 
      setTimeout(() => { }, 1000);
    }

    // or you can use the WindowService you create
    if (this.isBrowser) { 
      (<any>this.windowService).setTimeout(() => { }, 1000);
    }
  }
}

They WILL delay your Server-render, as Zones will be waiting

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Want more?

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For more Gotchas and other tips & tricks
Visit the Universal repo:

http://www.github.com/Angular/Universal

... More documentation coming soon ...

In Conclusion

  • SSR can help you avoid the "Loading" splash screen
    • Especially helpful on slower networks
  • On slower networks (3G / etc) you can get a faster initial paint and "perception" that the App's performance is much faster.
    • Can be ~ 2-3x faster "initial paint"
  • You can finally get SEO & Social-Media Previews
  • Be mindful of browser-specific things you might be using in your code!
    • Also make sure you choose 3rd party libraries carefully as well! For the same reason.

In Conclusion

We went from

To this:

As for the question of
"can we have the best of both worlds? "

Yes!

( with a little effort of course )

So ...

Thank You !

Follow me on Twitter
I'll post a link to the slides later

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@MarkPieszak
 

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Consulting / Training / Workshops / Development 

Angular Universal AngularCLI integration / Deep-Dive & Best Practices

By Mark Pieszak

Angular Universal AngularCLI integration / Deep-Dive & Best Practices

Deep-dive presentation on Angular Universal and common server-side rendering use-cases

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