AsyncQueue.ts

class QueueNode<T> {
  public promise: () => Promise<T>;
  public next: QueueNode<T> | null;
  public finished: boolean;
  constructor(promise: () => Promise<T>) {
    this.promise = promise;
  }
}

class AsyncQueue {
  private first: QueueNode<any>;
  private last: QueueNode<any>;

  constructor(initialNode: QueueNode<any>) {
    this.first = initialNode;
    this.last = initialNode;
  }

  public add<T>(item: QueueNode<T>) {
    if (this.first === this.last) {
      this.first.next = item;
      this.last = item;
    } else {
      this.last.next = item;
      this.last = item;
    }
  }

  public async run(onFullfill: (result: any) => void) {
    let current: QueueNode<any> | null = this.first;
    while (current !== null) {
      const result = await current.promise();
      onFullfill(result);
      current = current.next;
      if (current?.next === null) {
        this.first = current;
        this.last = current;
      }
    }
  }
}

const task1 = () =>
  new Promise((resolve) => setTimeout(() => resolve(1), 1000));
const task2 = () =>
  new Promise((resolve) => setTimeout(() => resolve(2), 2000));
const task3 = () =>
  new Promise((resolve) => setTimeout(() => resolve(3), 3000));

const node1 = new QueueNode(task1);
const node2 = new QueueNode(task2);
const node3 = new QueueNode(task3);

const queue = new AsyncQueue(node1);
queue.add(node2);
queue.add(node3);

queue.run((result) => console.log(result));