how does ES6 handle asynchronous requests

In ES6, you can use Promise objects to manage asynchronous requests. Promises are objects that represent asynchronous operations and can be used to obtain the results of those operations.

Here is an example of handling asynchronous requests using Promises:

function getData() {
  return new Promise((resolve, reject) => {
    // 异步请求代码
    setTimeout(() => {
      const data = '这是异步请求的数据';
      if (data) {
        resolve(data); // 异步请求成功，将数据传递给resolve函数
      } else {
        reject('请求失败'); // 异步请求失败，将错误信息传递给reject函数
      }
    }, 2000);
  });
}

// 调用异步请求函数
getData()
  .then(data => {
    console.log('异步请求成功:', data);
  })
  .catch(error => {
    console.error('异步请求失败:', error);
  });

In the example above, the getData function returns a Promise object which executes asynchronous request code in its constructor. If the asynchronous request is successful, the resolve function is called to pass the data; if it fails, the reject function is called to pass an error message.

You can use the .then() method to handle successful asynchronous requests and the .catch() method to handle failed asynchronous requests.

In the examples above, asynchronous requests are simulated using the setTimeout function, in reality, you can use XMLHttpRequest objects, the fetch API, or libraries like Axios for genuine asynchronous requests.