OpenNoodl/packages/noodl-viewer-react/src/async-queue.js

export default class ASyncQueue {
  constructor() {
    this.queue = [];
    this.pendingPromise = false;
  }

  enqueue(promise) {
    return new Promise((resolve, reject) => {
      this.queue.push({
        promise,
        resolve,
        reject
      });
      this.dequeue();
    });
  }

  dequeue() {
    if (this.workingOnPromise) {
      return false;
    }
    const item = this.queue.shift();
    if (!item) {
      return false;
    }
    try {
      this.workingOnPromise = true;
      item
        .promise()
        .then((value) => {
          this.workingOnPromise = false;
          item.resolve(value);
          this.dequeue();
        })
        .catch((err) => {
          this.workingOnPromise = false;
          item.reject(err);
          this.dequeue();
        });
    } catch (err) {
      this.workingOnPromise = false;
      item.reject(err);
      this.dequeue();
    }
    return true;
  }
}