A Deep Look at Angular Elements

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@ManfredSteyer A Deep Look at Angular Elements Manfred Steyer SOFTWAREarchitekt.at ManfredSteyer

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@ManfredSteyer ✓ Commodore 64 ✓ 1982 ✓ ~ 1 MHz ✓ 64 KB RAM ✓ Disks with 170 KB

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@ManfredSteyer Version with two cores ;-) Challenge: Resources!

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@ManfredSteyer Long Time Maintain- ability Maintain + Extend for 10 +/- yrs

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@ManfredSteyer There are milk products lasting longer than some JavaScript frameworks

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@ManfredSteyer Web Components

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@ManfredSteyer Contents • Web Components and Angular Elements • Polyfills • Dynamically adding Web Components • Loading external Web Components • Zone-less Change Detection • Content Projection and Slot API • Bonus: Using existing Web Components with Angular

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@ManfredSteyer Didactics • Presentations • Live-Coding • Labs

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@ManfredSteyer Labs • Regular labs: You just need a browser (Stackblitz) • Bonus labs for later: You need a local environment

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@ManfredSteyer About me… • Manfred Steyer • SOFTWAREarchitekt.at • Angular Trainings and Consultancy • Google Developer Expert (GDE) • Trusted Angular Collaborator Page ▪ 10 Manfred Steyer Public: Selected European Cities In-House: everywhere http://www.softwarearchitekt.at

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@ManfredSteyer Web Components and Angular Elements

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@ManfredSteyer Web Components: Framework independent components

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@ManfredSteyer Umbrella term for several standards

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@ManfredSteyer Standards behind Web Components Templates Shadow DOM Custom Elements Omnipresent in Angular Baked-in: @Component(encapsulation: …) Angular Elements

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@ManfredSteyer Angular Elements @NgModule({ imports: [BrowserModule], declarations: [MyComponent], entryComponents: [MyComponent] }) export class AppModule { }

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@ManfredSteyer Angular Elements @NgModule({ imports: [BrowserModule], declarations: [MyComponent], entryComponents: [MyComponent] }) export class MyModule { }

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@ManfredSteyer Angular Elements @NgModule({ imports: [BrowserModule], declarations: [MyComponent], entryComponents: [MyComponent] }) export class MyModule { constructor(private injector: Injector) { const MyElement = createCustomElement( MyComponent, { injector: this.injector }); customElements.define('my-element', MyElement); } }

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@ManfredSteyer Using an Angular Element

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@ManfredSteyer DEMO

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@ManfredSteyer Use the CUSTOM_ELEMENTS_SCHEMA @NgModule({ […], schemas: [ CUSTOM_ELEMENTS_SCHEMA ] }) export class AppModule { }

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@ManfredSteyer All this can be polyfilled down to IE11 (more or less)

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@ManfredSteyer Distribution

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@ManfredSteyer Polyfill

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@ManfredSteyer Selected Polyfills loader •Templates •Custom Elements •Shadow DOM es5-adapter •For browsers that DO support custom elements

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@ManfredSteyer DEMO

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@ManfredSteyer LAB https://tinyurl.com/elements-labs

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@ManfredSteyer Alternative to es5-adapter: Differential Loading CLI >= 8 ES 2015+ ES 5

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@ManfredSteyer 3 Steps 1. browserlist file: Add ES 5 browsers → e. g. IE9-11 2. tsconfig.json: Set target to ES2015 → "target":"ES2015" 3. Create a production build → ng build --prod

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@ManfredSteyer

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@ManfredSteyer How can browser decide?

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@ManfredSteyer Shadow DOM

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@ManfredSteyer Angular & Shadow DOM • Baked-in • Default: Emulation • @Component({ encapsulation: ViewEncapsulation.Emulated }) • Shadow DOM (v0) • @Component({ encapsulation: ViewEncapsulation.Native }) • Shadow DOM (v1) • @Component({ encapsulation: ViewEncapsulation.ShadowDom }) • Can be turned off: • @Component({ encapsulation: ViewEncapsulation.None })

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@ManfredSteyer DEMO

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@ManfredSteyer Dynamically adding custom elements

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@ManfredSteyer Adding Custom Elements const elm = document.createElement('my-element'); elm.setAttribute(…); elm['propertyName'] = …; elm.addEventListener(…); otherElement.appendChild(elm);

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@ManfredSteyer DEMO

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@ManfredSteyer LAB https://tinyurl.com/elements-labs

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@ManfredSteyer Loading External Elements

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@ManfredSteyer Simplest Script Loader on Earth const script = document.createElement('script'); script.src = 'assets/external-dashboard-tile.bundle.js‘; document.body.appendChild(script);

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@ManfredSteyer DEMO

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@ManfredSteyer LAB https://tinyurl.com/elements-labs

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@ManfredSteyer Skrinking your Bundles

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@ManfredSteyer How to deal with bundle size • Compiling UI-Code down with Ivy • Ivy integration for Elements is not part of Angular 8.0 • Sharing dependencies with ngx-build-plus • More: • See my yesterday’s talk (should be on youtube soon) • Bonus Labs (Director’s Cut)

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@ManfredSteyer Zone-less Change Detection

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@ManfredSteyer Why zone.js? • Used by Angular's changed detection • Patches each browser event • Notifies Angular after each event handler

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@ManfredSteyer Why not zone.js? • >100 KB (>10 KB gzipped) • Awkward to force consumers of our web components to load zone.js • Issues with native async/await (>=ES 2017)

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@ManfredSteyer How to exclude it? platformBrowserDynamic().bootstrapModule(AppModule, {ngZone: 'noop'})

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@ManfredSteyer Consequences • Manual Change Detection • Change Detection via Observables

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@ManfredSteyer DEMO

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@ManfredSteyer Content Projection & Slot API (Shadow DOM)

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@ManfredSteyer Panel

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@ManfredSteyer Implementation

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@ManfredSteyer Implementation

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@ManfredSteyer Calling a Tab Lorem ipsum, dolor sit amet …

Some extra info

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@ManfredSteyer Slot API • ShadowDOM v1 • ViewEncapsulation.ShadowDom

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@ManfredSteyer DEMO

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@ManfredSteyer LAB https://tinyurl.com/elements-labs

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@ManfredSteyer Bonus: Using Existing Custom Elements

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@ManfredSteyer You can databind to any Custom Element

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@ManfredSteyer Two-Way-Databinding is more complicated

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@ManfredSteyer Convention for Two-Way-Databinding Bridge the gap with directives!

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@ManfredSteyer DEMO

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@ManfredSteyer LAB https://tinyurl.com/elements-labs

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@ManfredSteyer Summary Polyfills & Custom_Element_Schema Shadow DOM Dynamically Adding Dynamic Loading Zone-less Change Detection Content Projection with Slots

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@ManfredSteyer Contact and Downloads [mail] [email protected] [web] SOFTWAREarchitekt.at [twitter] ManfredSteyer d Blog about this stuff Public: Selected European Cities In-House: everywhere http://www.softwarearchitekt.at