{static:true})el:ElementRef;constructor(private zone:NgZone,prviate cdr:ChangeDetectorRef){}OnInit(){ this.zone.runOutsideAngular(()=>{ fromEvent(this.el.natvieElement,'scroll').subscribe((e)=>{... if(...){ ... this.cdr.detectChange() } }) })} 在处理事件侦听...
上面的示例中,我们在测试代码中动态修改了 title 的值,测试运行失败,这是因为 Angular 并不知道测试改变了组件,ComponentFixtureAutoDetect 只对异步操作进行自动变化检测,例如 Promise、setTimeout、click 等DOM事件等,如果我们手动更改了绑定值,我们依然还需要调用fixture.detectChanges() 来执行变化检测。 常见的坑...
@Component({ template: `{{counter}} <input type="check" (click)="toggle()">`, }) class CartBadgeCmp { counter = 0; detectEnabled = false; constructor(private cd: ChangeDetectorRef) {} ngOnInit() { // 每10毫秒增加1 setInterval(()=>{this.counter++}, 10); } toggle(){ if( th...
ChangeDetectionStrategy 假若看了 LView check 标签、@Input value changed 都不需要 refreshView,那最后就看 ChangeDetectionStrategy。 每一个组件都有一个 ChangeDetectionStrategy(检测策略)设置。 如果ChangeDetectionStrategy 是 Default 那就 refreshView。 如果ChangeDetectionStrategy 是 OnPush 那就不 refreshView,与...
Angular detects changes to the @Input properties ngOnChanges(changes: SimpleChanges) { //Action for change } //Solution 2 - Where Angular fails to detect the changes to the input property //the DoCheck allows us to implement our custom change detection ngDoCheck() { //Action for change } ...
<input type="check" (click)="toggle()">`, })classCartBadgeCmp{ counter =0; detectEnabled =false;constructor(privatecd: ChangeDetectorRef) {}ngOnInit() {// 每10毫秒增加1setInterval(()=>{this.counter++},10); }toggle(){if(this.detectEnabled){this.cd.reattach();// 链接上变化检测树...
使用angular cli 生成一个组件,默认没有配置changeDetection ,也就是changeDetection 为默认值ChangeDetectionStrategy#Default, 正常情况应该没有什么问题,最近在工作中遇到一个比较复杂的组件,经过很长时间的版本迭代,用各种方法添加了各种业务实际需求但不长见到的功能。组件放到页面后,其他表单组件卡顿。翻看其他组件库的...
constructor(private zone:NgZone,prviate cdr:ChangeDetectorRef){} OnInit(){ this.zone.runOutsideAngular(()=>{ fromEvent(this.el.natvieElement,'scroll').subscribe((e)=>{... if(...){ ... this.cdr.detectChange() } }) }) }
// Displayed title is old because Angular didn't hear the change :( expect(h1.textContent).toContain(oldTitle); }); it('should display updated title after detectChanges', () => { comp.title = 'Test Title'; fixture.detectChanges(); // detect changes explicitly expect(h1.textContent).to...
comp.title='Test Title';// Displayed title is old because Angular didn't hear the change :(expect(h2.textContent).toContain(oldTitle); });it('should display updated title after detectChanges',() =>{ comp.title='Test Title'; fixture.detectChanges();// detect changes explicitlyexpect(h2.tex...