1. 基本的 GET 请求

fetch('https://api.example.com/data')
  .then(response => {
    if (!response.ok) {
      throw new Error('Network response was not ok ' + response.statusText);
    }
    return response.json();
  })
  .then(data => {
    console.log(data);
  })
  .catch(error => {
    console.error('There has been a problem with your fetch operation:', error);
  });

2. 使用 Async/Await

async function fetchData(url) {
  try {
    const response = await fetch(url);
    if (!response.ok) {
      throw new Error('Network response was not ok');
    }
    const data = await response.json();
    console.log(data);
  } catch (error) {
    console.error('There has been a problem with your fetch operation:', error);
  }
}

fetchData('https://api.example.com/data');

3. 发送 POST 请求

fetch('https://api.example.com/data', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    key1: 'value1',
    key2: 'value2',
  }),
})
.then(response => response.json())
.then(data => console.log(data))
.catch(error => console.error('Error:', error));

4. 错误处理

在处理 fetch 请求时，应该检查响应的 ok 属性，它是一个布尔值，指示响应的状态码是否在 200-299 的范围内。

fetch('https://api.example.com/data')
  .then(response => {
    if (!response.ok) {
      throw new Error('Network response was not ok');
    }
    return response.json();
  })
  .catch(error => console.error('Fetch error:', error));

5. 超时处理

fetch 原生不支持请求超时，但可以通过设置一个定时器来实现：

const fetchWithTimeout = (url, options, timeout = 7000) => {
  return Promise.race([
    fetch(url, options),
    new Promise((_, reject) =>
      setTimeout(() => reject(new Error('Timeout')), timeout)
    ),
  ]);
};

fetchWithTimeout('https://api.example.com/data')
  .then(response => response.json())
  .then(data => console.log(data))
  .catch(error => console.error('Error:', error));

6. 使用 AbortController 取消请求

在需要取消正在进行的请求时，可以使用 AbortController。

const controller = new AbortController();
const signal = controller.signal;

fetch('https://api.example.com/data', { signal })
  .then(response => response.json())
  .then(data => console.log(data))
  .catch(error => {
    if (error.name === 'AbortError') {
      console.log('Fetch aborted');
    } else {
      console.error('Fetch error:', error);
    }
  });

// 取消 fetch
controller.abort();