在ES6中使用类的单例

class Singleton {
  constructor(name) {
    if (!Singleton.instance) {
      this.name = name;
      Singleton.instance = this;
    }
    return Singleton.instance;
  }

  static getInstance(name) {
    if (!Singleton.instance) {
      Singleton.instance = new Singleton(name);
    }
    return Singleton.instance;
  }
}

// 使用示例
const instance1 = Singleton.getInstance('Instance 1');
console.log(instance1.name); // 输出: Instance 1

const instance2 = Singleton.getInstance('Instance 2');
console.log(instance2.name); // 输出: Instance 1

console.log(instance1 === instance2); // 输出: true

class ThreadSafeSingleton {
  constructor(name) {
    if (!ThreadSafeSingleton.instance) {
      this.name = name;
      ThreadSafeSingleton.instance = this;
    }
    return ThreadSafeSingleton.instance;
  }

  static async getInstance(name) {
    if (!ThreadSafeSingleton.instance) {
      // 使用Promise确保只有一个实例被创建
      await new Promise(resolve => setTimeout(resolve, 0));
      if (!ThreadSafeSingleton.instance) {
        ThreadSafeSingleton.instance = new ThreadSafeSingleton(name);
      }
    }
    return ThreadSafeSingleton.instance;
  }
}