docs(change-detection): add change detection dev guide

public/docs/_examples/change-detection/e2e-spec.ts

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+'use strict'; // necessary for es6 output in node
+
+import { browser, element, by, ExpectedConditions as EC } from 'protractor';
+
+describe('Change Detection guide', () => {
+
+  beforeEach(() => {
+
+    // setInterval() used in the code makes Protractor mistakenly think we're not
+    // finished loading unless we turn this on.
+    browser.ignoreSynchronization = true;
+
+    browser.get('/');
+    return browser.wait(EC.presenceOf(element(by.css('[ng-version]'))));
+  });
+
+  describe('Basic Example', () => {
+
+    it('displays a counter that can be incremented and decremented', () => {
+      const component = element(by.tagName('hero-counter'));
+      const counter = component.element(by.css('span'));
+
+      expect(counter.getText()).toEqual('5');
+
+      component.element(by.buttonText('+')).click();
+      expect(counter.getText()).toEqual('6');
+      component.element(by.buttonText('-')).click();
+      expect(counter.getText()).toEqual('5');
+    });
+
+  });
+
+  describe('Broken name badge example', () => {
+
+    it('causes an error', () => {
+      const errorDump = element(by.id('bootstrapError'));
+      expect(errorDump.getText()).toContain('HeroNameBadgeBrokenComponent');
+      expect(errorDump.getText()).toContain('Expression has changed after it was checked');
+    });
+
+    it('still displays the bound data', () => {
+      const component = element(by.tagName('hero-name-badge-broken'));
+      expect(component.element(by.css('h4')).getText()).toEqual('Anonymous details');
+    });
+
+  });
+
+  describe('Fixed name badge example', () => {
+
+    it('displays the bound data', () => {
+      const component = element(by.tagName('hero-name-badge'));
+      expect(component.element(by.css('h4')).getText()).toEqual('details');
+      expect(component.element(by.css('p')).getText()).toEqual('Name: Anonymous');
+    });
+
+  });
+
+  describe('OnPush', () => {
+
+    describe('with immutable string inputs', () => {
+
+      it('displays the bound data', () => {
+        const component = element(by.tagName('hero-search-result'));
+        const match = component.element(by.css('.match'));
+        expect(match.getText()).toEqual('indsto');
+      });
+
+    });
+
+    describe('with input mutations', () => {
+
+      it('does not display the mutations', () => {
+        const component = element(by.tagName('hero-manager-mutable'));
+
+        expect(component.element(by.cssContainingText('li', 'Windstorm')).isPresent()).toBe(true);
+        expect(component.element(by.cssContainingText('li', 'Magneta')).isPresent()).toBe(true);
+        component.element(by.buttonText('Add one more')).click();
+        expect(component.element(by.cssContainingText('li', 'Bombasto')).isPresent()).toBe(false);
+
+      });
+
+    });
+
+    describe('with immutable array input', () => {
+
+      it('displays the changes', () => {
+        const component = element(by.tagName('hero-manager-immutable'));
+
+        expect(component.element(by.cssContainingText('li', 'Windstorm')).isPresent()).toBe(true);
+        expect(component.element(by.cssContainingText('li', 'Magneta')).isPresent()).toBe(true);
+        component.element(by.buttonText('Add one more')).click();
+        expect(component.element(by.cssContainingText('li', 'Bombasto')).isPresent()).toBe(true);
+
+      });
+
+    });
+
+    describe('with events', () => {
+
+      it('displays the changes', () => {
+        const component = element(by.tagName('hero-counter-onpush'));
+        const counter = component.element(by.css('span'));
+
+        expect(counter.getText()).toEqual('5');
+
+        component.element(by.buttonText('+')).click();
+        expect(counter.getText()).toEqual('6');
+        component.element(by.buttonText('-')).click();
+        expect(counter.getText()).toEqual('5');
+      });
+
+    });
+
+    describe('with explicit markForDetection()', () => {
+
+      it('does not detect setInterval() when not used', () => {
+        const component = element(by.tagName('hero-counter-auto-broken'));
+        browser.sleep(300); // There's an interval of 100ms inside the component.
+        expect(component.getText()).toEqual('Number of heroes: 5');
+      });
+
+      it('does detect setInterval() when used', () => {
+        const component = element(by.tagName('hero-counter-auto'));
+        browser.sleep(300); // There's an interval of 100ms inside the component.
+        expect(component.getText()).not.toEqual('Number of heroes: 5');
+        expect(component.getText()).toMatch(/Number of heroes: \d+/);
+      });
+
+      it('detects on evented library callbacks', () => {
+        const component = element(by.tagName('hero-name-badge-evented'));
+        expect(component.element(by.cssContainingText('h4', 'Windstorm details')).isPresent()).toBe(true);
+        element(by.buttonText('Rename')).click();
+        expect(component.element(by.cssContainingText('h4', 'Magneta details')).isPresent()).toBe(true);
+      });
+
+    });
+
+    describe('detached', () => {
+
+      it('does not pick up changes automatically', () => {
+        const component = element(by.tagName('hero-name-badge-detached'));
+        expect(component.element(by.css('h4')).getText()).toEqual('Windstorm details');
+        element(by.buttonText('Rename detached')).click();
+        expect(component.element(by.css('h4')).getText()).toEqual('Windstorm details');
+      });
+
+      it('starts picking up changes again when reattached', () => {
+        const component = element(by.tagName('hero-counter-live'));
+        const count = component.element(by.css('.count'));
+
+        const text1 = count.getText();
+        browser.sleep(100);
+        component.element(by.buttonText('Toggle live update')).click();
+        const text2 = count.getText();
+        browser.sleep(100);
+        const text3 = count.getText();
+
+        expect(text1).not.toEqual(text2);
+        expect(text2).toEqual(text3);
+      });
+
+      it('can be used for throttling by explicitly detecting with an interval', () => {
+        const component = element(by.tagName('hero-counter-throttled'));
+        const count = component.element(by.css('.count'));
+
+        const text1 = count.getText();
+        browser.sleep(100);
+        const text2 = count.getText();
+        browser.sleep(100);
+        const text3 = count.getText();
+
+        Promise.all([text1, text2, text3]).then(([t1, t2, t3]) => {
+          let differences = 0;
+          if (t1 !== t2) differences++;
+          if (t2 !== t3) differences++;
+          expect(differences).toBeLessThan(2);
+        });
+      });
+
+    });
+
+
+
+
+  });
+
+});

public/docs/_examples/change-detection/ts/src/app/app.component.ts

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+import { Component } from '@angular/core';
+import { Hero } from './hero.model';
+import { HeroModel } from './onpush/hero-evented.model';
+
+@Component({
+  moduleId: module.id,
+  selector: 'hero-app',
+  template: `
+    <h1>Angular Change Detection</h1>
+
+
+    <h2>Basic Example</h2>
+    <hero-counter>
+    </hero-counter>
+
+    <h2>Single-Pass</h2>
+
+    <h3>Broken Example</h3>
+    <hero-name-badge-broken [hero]="anonymousHero">
+    </hero-name-badge-broken>
+
+    <h3>Fixed Example</h3>
+    <hero-name-badge [hero]="secondAnonymousHero">
+    </hero-name-badge>
+
+
+    <h2>OnPush</h2>
+
+    <h3>Immutable Primitive Values</h3>
+    <p>OnPush only runs detection when inputs change.</p>
+    <hero-search-result [searchResult]="'Windstorm'" [searchTerm]="'indsto'">
+    </hero-search-result>
+
+
+    <h3>Mutable Collection, Broken Example</h3>
+    <p>OnPush does not detect changes inside array inputs.</p>
+    <hero-manager-mutable>
+    </hero-manager-mutable>
+
+    <h3>Immutable Collection, Fixed Example</h3>
+    <p>OnPush detects changes for array inputs as longs as they're treated as immutable values.</p>
+    <hero-manager-immutable>
+    </hero-manager-immutable>
+
+    <h3>Events</h3>
+    <p>OnPush detects changes when they originate in an event handler.</p>
+    <hero-counter-onpush>
+    </hero-counter-onpush>
+
+
+    <h3>Explicit Change Marking, Broken Without</h3>
+    <p>A counter incrementing with setTimeout() inside an OnPush component does not update.</p>
+    <hero-counter-auto-broken>
+    </hero-counter-auto-broken>
+
+    <h3>Explicit Change Marking</h3>
+    <p>This is fixed using markForCheck()</p>
+    <hero-counter-auto>
+    </hero-counter-auto>
+
+    <h3>Explicit Change Marking with Library Callback</h3>
+    <hero-name-badge-evented [hero]="heroModel">
+    </hero-name-badge-evented>
+    <button (click)="renameHeroModel()">Rename</button>
+
+
+    <h2>Detaching</h2>
+
+    <h3>Permanently, "One-Time Binding"</h3>
+    <p>By detaching a component's change detector at ngOnInit() we can do "one-time binding".</p>
+    <hero-name-badge-detached [hero]="hero">
+    </hero-name-badge-detached>
+    <button (click)="renameHero()">Rename detached</button>
+
+    <h3>Temporarily, reattach</h3>
+    <p>By detaching/reattaching a change detector we can toggle whether a component has "live updates".</p>
+    <hero-counter-live>
+    </hero-counter-live>
+
+    <h3>Throttling with Internal detectChanges</h3>
+    <p>
+      By calling detectChanges() on a detached change detector we can choose when change detection is done.
+      This can be used to update the view at a lower frequency than data changes.
+    </p>
+    <hero-counter-throttled>
+    </hero-counter-throttled>
+
+    <h3>Flushing to DOM with Internal detectChanges</h3>
+    <p>We can use detectChanges() to flush changes to the view immediately if we can't wait for the next turn of the zone.</p>
+    <hero-signature-form>
+    </hero-signature-form>
+
+    <h2>Escaping NgZone For Async Work</h2>
+
+    <h3>Without</h3>
+    <p>Many unnecessary change detections will be performed for this workflow because it is all inside NgZone.</p>
+    <hero-async-workflow></hero-async-workflow>
+  `
+})
+export class AppComponent {
+  hero: Hero = {name: 'Windstorm', onDuty: true};
+  anonymousHero: Hero = {name: '', onDuty: false};
+  secondAnonymousHero: Hero = {name: '', onDuty: false};
+
+  heroModel = new HeroModel('Windstorm');
+
+  renameHero() {
+    this.hero.name = 'Magneta';
+  }
+
+  renameHeroModel() {
+    this.heroModel.setName('Magneta');
+  }
+
+}

public/docs/_examples/change-detection/ts/src/app/app.module.ts

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+import { NgModule } from '@angular/core';
+import { BrowserModule } from '@angular/platform-browser';
+import { FormsModule } from '@angular/forms';
+
+import { AppComponent } from './app.component';
+
+import { HeroCounterComponent } from './hero-counter.component';
+import { HeroNameBadgeBrokenComponent } from './hero-name-badge.broken.component';
+import { HeroNameBadgeComponent } from './hero-name-badge.component';
+import { SearchResultComponent } from './onpush/search-result.component';
+import { HeroListComponent as HeroListOnpushComponent } from './onpush/hero-list.onpush.component';
+import { HeroManagerMutableComponent } from './onpush/hero-manager.mutable.component';
+import { HeroManagerImmutableComponent } from './onpush/hero-manager.immutable.component';
+import { HeroCounterComponent as HeroCounterOnPushComponent } from './onpush/hero-counter.onpush.component';
+import { HeroCounterAutoComponent as HeroCounterAutoBrokenComponent } from './onpush/hero-counter-auto.broken.component';
+import { HeroCounterAutoComponent } from './onpush/hero-counter-auto.component';
+import { HeroNameBadgeComponent as HeroNameBadgeEventedComponent } from './onpush/hero-name-badge-evented.component';
+import { HeroNameBadgeComponent as HeroNameBadgeDetachedComponent } from './detach/hero-name-badge-detached.component';
+import { HeroCounterComponent as HeroCounterLiveComponent } from './detach/hero-counter-live.component';
+import { HeroCounterComponent as HeroCounterThrottledComponent } from './detach/hero-counter-throttled.component';
+import { HeroSignatureFormComponent } from './detach/hero-signature-form.component';
+import { AsyncWorkflowComponent } from './async-workflow.component';
+
+@NgModule({
+  imports: [
+    BrowserModule,
+    FormsModule
+  ],
+  declarations: [
+    AppComponent,
+    HeroCounterComponent,
+    HeroNameBadgeBrokenComponent,
+    HeroNameBadgeComponent,
+    SearchResultComponent,
+    HeroListOnpushComponent,
+    HeroManagerMutableComponent,
+    HeroManagerImmutableComponent,
+    HeroCounterOnPushComponent,
+    HeroCounterAutoBrokenComponent,
+    HeroCounterAutoComponent,
+    HeroNameBadgeEventedComponent,
+    HeroNameBadgeDetachedComponent,
+    HeroCounterLiveComponent,
+    HeroCounterThrottledComponent,
+    HeroSignatureFormComponent,
+    AsyncWorkflowComponent
+  ],
+  bootstrap: [
+    AppComponent
+  ]
+})
+export class AppModule { }