ngx-zone-scheduler

A SchedulerLike implementation for use with Angular and rxjs.

Purpose

When an Angular component subscribes to an Observable data source, the callback will run outside of the Angular zone. If updates are made to the component within the callback, Angular may not detect the changes. This can lead to many strange problems that can be difficult to debug.

This module provides a SchedulerLike implementation that will run your callbacks in the Angular zone so the changes will be detected. It can be injected into your services so your components don't need to worry about zones.

This module should be fully AoT compatible. It is extremely lightweight, as all of its runtime dependencies are peerDependencies.

Usage

Register the ZoneSchedulerModule as an import with your AppModule

In app.module.ts:

import { NgModule } from '@angular/core';
import { ZoneSchedulerModule } from 'ngx-zone-scheduler';
 
@NgModule( {
    imports: [ ZoneSchedulerModule ]
    // additional module metadata (declarations, bootstrap, etc)
} )
export class AppModule {}

In your services:

import { Inject } from '@angular/core';
import { Observable, SchedulerLike } from 'rxjs';
import { observeOn } from 'rxjs/operators';
import { ZoneScheduler } from 'ngx-zone-scheduler';
 
export class FooService {
    public constructor(
        @Inject( ZoneScheduler )
        private readonly scheduler: SchedulerLike
    ) {}
 
    private data: Observable<{}>; // TODO: initialize data source
 
    public foo() {
        return this.data.pipe( observeOn( this.scheduler ) );
    }
}

Alternative Usage

You may also choose to inject ZoneScheduler directly into your components, and pipe to observeOn from the consumer rather than the producer. This approach is less encapsulated, though, and has an increased surface area for maintenance and testing.

It's also possible to construct ZoneScheduler without ZoneSchedulerModule. You can simply pass an instance of NgZone to the ZoneScheduler constructor. ZoneSchedulerModule simply registers a provider for ZoneScheduler dependency injection.