Scheduler for limit Promises

Scheduler.js

class Scheduler {
  constructor(limit) {
    this.count = 0;
    this.limit = limit;
    this.list = [];
  }
  add(fn) {
    return new Promise((resolve) => {
      this.list.push((...args) => fn(...args).then(resolve));
      this.run();
    });
  }
  async run() {
    if (this.count === this.limit || this.list.length === 0) return;

    this.count++;
    await this.list.shift()();
    this.count--;

    this.run();
  }
}

export default Scheduler;