widjet-disposables/src/index.js

Lightweight disposable pattern implementation

export class Disposable {
  constructor(block) {
    if (!block) {
      throw new Error('A Disposable must be created with a dispose callback');
    }
    this.block = block;
  }

  dispose() {
    if (this.block) {
      this.block();
      delete this.block;
    }
  }
}

export class CompositeDisposable extends Disposable {
  constructor(disposables = []) {
    super(() => {
      for (let i = 0; i < this.disposables.length; i++) {
        const disposable = this.disposables[i];
        disposable.dispose();
      }
    });

    this.disposables = disposables;
  }

  add(disposable) { this.disposables.push(disposable); }

  remove(disposable) {
    const index = this.disposables.indexOf(disposable);

    if (index !== -1) { this.disposables.splice(index, 1); }
  }
}

export class DisposableEvent extends Disposable {
  constructor(target, event, listener) {
    const events = event.split(/\s+/g);

    if (typeof target.addEventListener === 'function') {
      super(() => events.forEach(e => target.removeEventListener(e, listener)));
      events.forEach(e => target.addEventListener(e, listener));
    } else if (typeof target.on === 'function') {
      super(() => events.forEach(e => target.off(e, listener)));
      events.forEach(e => target.on(e, listener));
    } else {
      throw new Error('The passed-in source must have either a addEventListener or on method');
    }
  }
}