What is rx-scavenger?

rx-scavenger is an RxJS Subscription Garbage Collector.

Its main goal is to reduce the boilerplate code when handling RxJS Subscriptions in Angular components in an easy and safe way.

rx-scavenger also allows you to map Subscriptions to a key and every time that you subscribe to a new Observable using the same key, the previous Subscription will automatically be unsubscribed of.

This easily avoids some race conditions and memory leaks when overwriting Subscriptions.

Getting Started

Install

yarn add @wishtack/rx-scavenger

or npm install --save @wishtack/rx-scavenger

Usage in an Angular component

import { Scavenger } from '@wishtack/rx-scavenger';

@Component({
    ...
})
export class WeatherComponent implements OnDestroy, OnInit {
    
    private _scavenger = new Scavenger(this);
    
    constructor(private _weatherStation: WeatherStation) {
    }
    
    ngOnInit() {
        
        this._weatherStation
            .getWeather('Lyon')
            .pipe(
                this._scavenger.collect()        
            )
            .subscribe(weather => {
                ...
            });
        
    }
    
    ngOnDestroy() {
    }
    
}

As you can see, there's no need to call Scavenger.unsubscribe() in ngOnDestroy() method as the Scavenger class takes care of implementing it and collecting every Subscription to the Observable returned by WeatherStation.getWeather() using the Scavenger.collect() method.

Using collectByKey to avoid overwritten Subscriptions

    refreshWeather(city) {
        
        this._subscription = this._weatherStation
            .getWeather(city)
            .subscribe(weather => {
                ...
            });
        
    }

Usually, if the WeatherComponent.refreshWeather() method here is called more than once, we might end up in a race condition or simply overwrite the Subscription in _subscription property.

Race condition issues also happen when using takeUntil(destroyed$) pattern.

Using the Scavenger.collectByKey(key: string) method, the first Subscription is stored in a Map with that key and on the second subscribe, the first Subscription is unsubscribed from so there's only one Subscription open with that key at a time.

    refreshWeather(city) {
        
        this._weatherStation
            .getWeather(city)
            .pipe(
                this._scavenger.collectByKey('weather')        
            )
            .subscribe(weather => {
                ...
            });
        
    }

Manual Unsubscribe

You can also unsubscribe from all the collected Subscriptions using Scavenger.unsubscribe().