const TELEGRAPH_URL = 'https://api.openai.com';

addEventListener('fetch', event => {
  event.respondWith(handleRequest(event.request))
})

async function handleRequest(request) {
  const url = new URL(request.url);
  url.host = TELEGRAPH_URL.replace(/^https?:\/\//, '');
  const modifiedRequest = new Request(url.toString(), {
    headers: request.headers,
    method: request.method,
    body: request.body,
    redirect: 'follow'
  });
  const response = await fetch(modifiedRequest);
  const modifiedResponse = new Response(response.body, response);
  // 添加允许跨域访问的响应头
  modifiedResponse.headers.set('Access-Control-Allow-Origin', '*');
  return modifiedResponse;
}

不会使用的话，请查阅相关文档