asyncQueue.js

class AsyncQueue {
    #queue = [];
    #maxQueueLength = Infinity;
    #nextResolve = () => {};
    #hasNext = false;
  
    constructor(maxQueueLength) {
      if (maxQueueLength) {
        this.#maxQueueLength = maxQueueLength;
      }
    }
  
    async *[Symbol.asyncIterator]() {
      while (true) {
        yield new Promise((resolve) => {
          if (this.#queue.length > 0) {
            return resolve(this.#queue.shift());
          }
          this.#nextResolve = resolve;
          this.#hasNext = true;
        });
      }
    }
  
    push(item) {
      if (this.#hasNext) {
        this.#nextResolve(item);
        this.#hasNext = false;
        return;
      }
      if (this.#queue.length > this.#maxQueueLength) {
        this.#queue.shift();
      }
      this.#queue.push(item);
    }
  }
  
  (async function () {
    const queue = new AsyncQueue();
  
    setInterval(() => {
      queue.push(Date.now().toString());
      queue.push(Date.now().toString() + "++");
    }, 1000);
  
    for await (const evt of queue) {
      console.log(evt);
    }
  })();

asyncQueue.ts

class AsyncQueue<T> {
  private queue: T[] = [];
  private maxQueueLength = Infinity;
  private nextResolve = (value: T) => {};
  private hasNext = false;

  constructor(maxQueueLength?: number) {
    if (maxQueueLength) {
      this.maxQueueLength = maxQueueLength;
    }
  }

  async *[Symbol.asyncIterator]() {
    while (true) {
      yield new Promise((resolve) => {
        if (this.queue.length > 0) {
          return resolve(this.queue.shift());
        }
        this.nextResolve = resolve;
        this.hasNext = true;
      });
    }
  }

  push(item: T) {
    if (this.hasNext) {
      this.nextResolve(item);
      this.hasNext = false;
      return;
    }
    if (this.queue.length > this.maxQueueLength) {
      this.queue.shift();
    }
    this.queue.push(item);
  }
}

(async function () {
  const queue = new AsyncQueue<string>();

  setInterval(() => {
    queue.push(Date.now().toString());
    queue.push(Date.now().toString() + "++");
  }, 1000);

  for await (const evt of queue) {
    console.log(evt);
  }
})();