Async Queue

async-queue.js

import createCancellationToken from './createCancellationToken';

export default class AsyncQueue {
  process = createCancellationToken()

  _tasks = [];

  enqueue(...newTasks) {
    this._tasks.push(...newTasks);

    return this;
  }

  flush() {
    this.process.cancel();

    this._tasks.splice(0, this._tasks.length);

    return this;
  }

  async run() {
    let prevResult;

    let task = this._tasks[0];

    this.process = createCancellationToken();

    while (!this.process.isCancelled() && task) {
      prevResult = await task(this.process, prevResult);

      this._tasks.shift();

      task = this._tasks[0];
    }
  }
}

create-cancellation-token.js

const createCancellationToken = () => {
  let cancelled = false;

  return {
    isCancelled() {
      return cancelled;
    },
    cancel() {
      cancelled = true;
    },
  };
};

export default createCancellationToken;