How to Implement Debouncing in Angular?-JS Tutorial-php.cn

How to Implement Debouncing in Angular?

Barbara Streisand

Release： 2024-10-23 12:35:30

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How to Implement Debouncing in Angular?

Debouncing in Angular

Question:

How can debounce be implemented in Angular?

Answer:

In Angular 2 , debouncing can be achieved using RxJS operators on form control value changes. For example:

<code class="typescript">import {Component}   from '@angular/core';
import {FormControl} from '@angular/forms';
import {Observable}  from 'rxjs/Observable';
import 'rxjs/add/operator/debounceTime';

@Component({
  selector: 'my-app',
  template: `<input type=text [value]="firstName" [formControl]="firstNameControl">
    <br>{{firstName}}`
})
export class AppComponent {
  firstName        = 'Name';
  firstNameControl = new FormControl();
  ngOnInit() {
    this.firstNameControl.valueChanges
      .debounceTime(1000)
      .subscribe(newValue => this.firstName = newValue);
  }
}</code>

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This code debounces keystroke events with a delay of 1000 milliseconds.

Optimization Techniques:

While the above approach is valid, it can trigger change detection unnecessarily. For efficiency, consider creating RxJS Observables outside of Angular's change detection zone and manually calling ChangeDetectorRef.detectChanges().

<code class="typescript">import {Component, NgZone, ChangeDetectorRef, ApplicationRef, 
        ViewChild, ElementRef} from '@angular/core';
import {Observable} from 'rxjs/Observable';
import 'rxjs/add/operator/debounceTime';

@Component({
  selector: 'my-app',
  template: `<input #input type=text [value]="firstName">
    <br>{{firstName}}`
})
export class AppComponent {
  ngAfterViewInit() {
    Observable.fromEvent(this.inputElRef.nativeElement, 'keyup')
      .debounceTime(1000)
      .subscribe(keyboardEvent => {
        this.firstName = keyboardEvent.target.value;
        this.cdref.detectChanges();
      });
  }
}</code>

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This approach prevents unnecessary change detection, improving performance.

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