NgZone

Class Description

An injectable service for executing work inside or outside of the Angular zone.

The most common use of this service is to optimize performance when starting a work consisting of one or more asynchronous tasks that don't require UI updates or error handling to be handled by Angular. Such tasks can be kicked off via runOutsideAngular and if needed, these tasks can reenter the Angular zone via run.

Example (live demo)

import {Component, View, NgZone} from '@angular/core';
import {NgIf} from '@angular/common';

@Component({
  selector: 'ng-zone-demo'.
  template: `
    <h2>Demo: NgZone</h2>

    <p>Progress: {{progress}}%</p>
    <p *ngIf="progress >= 100">Done processing {{label}} of Angular zone!</p>

    <button (click)="processWithinAngularZone()">Process within Angular zone</button>
    <button (click)="processOutsideOfAngularZone()">Process outside of Angular zone</button>
  `,
  directives: [NgIf]
})
export class NgZoneDemo {
  progress: number = 0;
  label: string;

  constructor(private _ngZone: NgZone) {}

  // Loop inside the Angular zone
  // so the UI DOES refresh after each setTimeout cycle
  processWithinAngularZone() {
    this.label = 'inside';
    this.progress = 0;
    this._increaseProgress(() => console.log('Inside Done!'));
  }

  // Loop outside of the Angular zone
  // so the UI DOES NOT refresh after each setTimeout cycle
  processOutsideOfAngularZone() {
    this.label = 'outside';
    this.progress = 0;
    this._ngZone.runOutsideAngular(() => {
      this._increaseProgress(() => {
      // reenter the Angular zone and display done
      this._ngZone.run(() => {console.log('Outside Done!') });
    }}));
  }


  _increaseProgress(doneCallback: () => void) {
    this.progress += 1;
    console.log(`Current progress: ${this.progress}%`);

    if (this.progress < 100) {
      window.setTimeout(() => this._increaseProgress(doneCallback)), 10)
    } else {
      doneCallback();
    }
  }
}

Constructor

constructor({enableLongStackTrace = false}: any)

Static Members

isInAngularZone() : boolean

assertInAngularZone() : void

assertNotInAngularZone() : void