@angular/core

NgZone

Class

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

API

  
    class NgZone {}

hasPendingMacrotasks

boolean

hasPendingMicrotasks

boolean

isStable

boolean

Whether there are no outstanding microtasks or macrotasks.

onUnstable

EventEmitter<any>

Notifies when code enters Angular Zone. This gets fired first on VM Turn.

onMicrotaskEmpty

EventEmitter<any>

Notifies when there is no more microtasks enqueued in the current VM Turn. This is a hint for Angular to do change detection, which may enqueue more microtasks. For this reason this event can fire multiple times per VM Turn.

onStable

EventEmitter<any>

Notifies when the last onMicrotaskEmpty has run and there are no more microtasks, which implies we are about to relinquish VM turn. This event gets called just once.

onError

EventEmitter<any>

Notifies that an error has been delivered.

run

T

Executes the fn function synchronously within the Angular zone and returns value returned by the function.

Running functions via run allows you to reenter Angular zone from a task that was executed outside of the Angular zone (typically started via runOutsideAngular).

Any future tasks or microtasks scheduled from within this function will continue executing from within the Angular zone.

If a synchronous error happens it will be rethrown and not reported via onError.

@paramfn(...args: any[]) => T

@paramapplyThisany

@paramapplyArgsany[] | undefined

@returnsT

runTask

T

Executes the fn function synchronously within the Angular zone as a task and returns value returned by the function.

Running functions via runTask allows you to reenter Angular zone from a task that was executed outside of the Angular zone (typically started via runOutsideAngular).

Any future tasks or microtasks scheduled from within this function will continue executing from within the Angular zone.

If a synchronous error happens it will be rethrown and not reported via onError.

@paramfn(...args: any[]) => T

@paramapplyThisany

@paramapplyArgsany[] | undefined

@paramnamestring | undefined

@returnsT

runGuarded

T

Same as run, except that synchronous errors are caught and forwarded via onError and not rethrown.

@paramfn(...args: any[]) => T

@paramapplyThisany

@paramapplyArgsany[] | undefined

@returnsT

runOutsideAngular

T

Executes the fn function synchronously in Angular's parent zone and returns value returned by the function.

Running functions via runOutsideAngular allows you to escape Angular's zone and do work that doesn't trigger Angular change-detection or is subject to Angular's error handling.

Any future tasks or microtasks scheduled from within this function will continue executing from outside of the Angular zone.

Use run to reenter the Angular zone and do work that updates the application model.

@paramfn(...args: any[]) => T

@returnsT

isInAngularZone

boolean

This method checks whether the method call happens within an Angular Zone instance.

@returnsboolean

assertInAngularZone

void

Assures that the method is called within the Angular Zone, otherwise throws an error.

@returnsvoid

assertNotInAngularZone

void

Assures that the method is called outside of the Angular Zone, otherwise throws an error.

@returnsvoid

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.

Usage Notes

Example

          import {Component, 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>  `,})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();    }  }}