86 lines
2.4 KiB
TypeScript
86 lines
2.4 KiB
TypeScript
import {
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AfterContentChecked,
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AfterContentInit,
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AfterViewChecked,
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AfterViewInit,
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DoCheck,
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OnChanges,
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OnDestroy,
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OnInit,
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SimpleChanges
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} from '@angular/core';
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import { Component, Input } from '@angular/core';
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import { LoggerService } from './logger.service';
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let nextId = 1;
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// #docregion ngOnInit
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export class PeekABoo implements OnInit {
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constructor(private logger: LoggerService) { }
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// implement OnInit's `ngOnInit` method
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ngOnInit() { this.logIt(`OnInit`); }
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logIt(msg: string) {
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this.logger.log(`#${nextId++} ${msg}`);
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}
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}
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// #enddocregion ngOnInit
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@Component({
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selector: 'peek-a-boo',
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template: '<p>Now you see my hero, {{name}}</p>',
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styles: ['p {background: LightYellow; padding: 8px}']
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})
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// Don't HAVE to mention the Lifecycle Hook interfaces
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// unless we want typing and tool support.
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export class PeekABooComponent extends PeekABoo implements
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OnChanges, OnInit, DoCheck,
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AfterContentInit, AfterContentChecked,
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AfterViewInit, AfterViewChecked,
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OnDestroy {
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@Input() name: string;
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private verb = 'initialized';
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constructor(logger: LoggerService) {
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super(logger);
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let is = this.name ? 'is' : 'is not';
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this.logIt(`name ${is} known at construction`);
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}
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// only called for/if there is an @input variable set by parent.
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ngOnChanges(changes: SimpleChanges) {
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let changesMsgs: string[] = [];
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for (let propName in changes) {
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if (propName === 'name') {
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let name = changes['name'].currentValue;
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changesMsgs.push(`name ${this.verb} to "${name}"`);
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} else {
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changesMsgs.push(propName + ' ' + this.verb);
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}
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}
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this.logIt(`OnChanges: ${changesMsgs.join('; ')}`);
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this.verb = 'changed'; // next time it will be a change
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}
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// Beware! Called frequently!
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// Called in every change detection cycle anywhere on the page
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ngDoCheck() { this.logIt(`DoCheck`); }
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ngAfterContentInit() { this.logIt(`AfterContentInit`); }
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// Beware! Called frequently!
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// Called in every change detection cycle anywhere on the page
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ngAfterContentChecked() { this.logIt(`AfterContentChecked`); }
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ngAfterViewInit() { this.logIt(`AfterViewInit`); }
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// Beware! Called frequently!
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// Called in every change detection cycle anywhere on the page
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ngAfterViewChecked() { this.logIt(`AfterViewChecked`); }
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ngOnDestroy() { this.logIt(`OnDestroy`); }
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}
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