ngx-hook

ngx-hook is a small utility library for Angular. It provides a decorator Hook that emit on an EventEmitter. It is particularly useful for unsubscribing from observable streams in a functional way.

This may be a temporary project as this (angular/angular#13248) may solve it in the future.

Installation

npm

$ npm install ngx-hook --save

yarn

$ yarn add ngx-hook

Usage

Note: this example can actually be achieved with the async pipe.

import { Component, EventEmitter, OnInit, OnDestroy } from '@angular/core';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/observable/timer';

import { Hook } from 'ngx-hook';


@Component({
  selector: 'counter',
  template: '{{ counter }}'
})
export class CounterComponent implements OnInit, OnDestroy {

  // You don't need to instantiate it yourself
  // If you don't instantiate it, it will be instantiated before ngOnInit is called
  @Hook() ngOnDestroy$ = new EventEmitter<any>();

  counter: number = 0;

  ngOnInit () {
    Observable
      .timer(0, 1000)
      .takeUntil(this.ngOnDestroy$)
      .subscribe((value) => { this.counter = value; });
  }

  // For AOT you need to provide an empty method even if you don't use it, otherwise it will not get called by the framework.
  ngOnDestroy () {}
}

You can hook to any lifecycle hook that you want. By default it will hook to ngOnDestroy as it's the more useful one. Just pass the name of the hook in the Hook decorator like: @Hook('ngOnChanges').