如何用JavaScript实现一个支持并发控制的请求队列？

class ConcurrentQueue {
  constructor(maxConcurrency) {
    this.maxConcurrency = maxConcurrency;
    this.running = 0;
    this.queue = [];
  }

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

  run() {
    while (this.running < this.maxConcurrency && this.queue.length) {
      const { task, resolve, reject } = this.queue.shift();
      this.running++;

      task()
        .then(resolve)
        .catch(reject)
        .finally(() => {
          this.running--;
          this.run(); // 执行下一个任务
        });
    }
  }
}

// 示例
const queue = new ConcurrentQueue(3); // 最大并发数为 3

const fetchData = (url) => {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      const random = Math.random();
      if (random > 0.2) {
        console.log(`Fetching ${url} completed`);
        resolve(`Data from ${url}`);
      } else {
        console.error(`Fetching ${url} failed`);
        reject(`Failed to fetch ${url}`);
      }

    }, Math.random() * 1000); // 模拟网络延迟
  });
};

const urls = [
  "https://example.com/1",
  "https://example.com/2",
  "https://example.com/3",
  "https://example.com/4",
  "https://example.com/5",
  "https://example.com/6",
];

urls.forEach(url => {
  queue.enqueue(() => fetchData(url))
    .then(data => console.log("Result:", data))
    .catch(error => console.error("Error:", error));
});

  task()
        .then(resolve)
        .catch(error => {
          console.error(`Task failed: ${error}`);
          reject(error); // 将错误传递给 Promise
        })
        .finally(() => {
          this.running--;
          this.run(); // 执行下一个任务
        });

  setMaxConcurrency(newMaxConcurrency) {
    this.maxConcurrency = newMaxConcurrency;
    this.run(); // 尝试启动更多任务
  }