用JavaScript 实现一个简单的 Promise 并打印结果

以下是一个用 JavaScript 实现的简单 Promise 并打印结果的示例代码：

class MyPromise {
   
  constructor(executor) {
   
    this.status = 'pending';
    this.value = undefined;
    this.reason = undefined;

    const resolve = (value) => {
   
      if (this.status === 'pending') {
   
        this.status = 'fulfilled';
        this.value = value;
      }
    };

    const reject = (reason) => {
   
      if (this.status === 'pending') {
   
        this.status = 'ejected';
        this.reason = reason;
      }
    };

    try {
   
      executor(resolve, reject);
    } catch (error) {
   
      reject(error);
    }
  }
}

// 创建一个 Promise 实例
const myPromise = new MyPromise((resolve, reject) => {
   
  setTimeout(() => {
   
    resolve('Promise 成功了！');
  }, 1000);
});

// 监听 Promise 的状态变化
myPromise.then((result) => {
   
  console.log(result);
}).catch((error) => {
   
  console.error(error);
});