javascript - 错误: Request object that has already been used

Question

我不断在控制台日志中收到此错误

未捕获( promise 中)类型错误:无法在“ServiceWorkerGlobalScope”上执行“fetch”:无法使用已使用的请求对象构造请求。

我尝试更改我的 Service Worker 但不起作用

self.addEventListener('install', (event) => event.waitUntil(preLoad()));

const preLoad = function () {
  return caches.open('cc-offline').then((cache) => {
    return cache.addAll(['/offline.html', '/index.html']);
  });
}

self.addEventListener('fetch', (event) => {
  event.respondWith(checkResponse(event.request).catch(function () {
    return returnFromCache(event.request)
  }));
  event.waitUntil(addToCache(event.request));
});

const checkResponse = (request) => {
  return new Promise((fulfill, reject) => {
    fetch(request).then((response) => {
      (response.status !== 404) ? fulfill(response) : reject()
    }, reject)
  });
};

const addToCache = (request) => {
  return caches.open('cc-offline').then((cache) => {
    return fetch(request).then((response) => {
      return cache.put(request, response);
    });
  });
};

const returnFromCache = (request) => {
  return caches.open('cc-offline').then((cache) => {
    return cache.match(request).then((matching) => {
      return (!matching || matching.status == 404) ? cache.match('offline.html') : matching
    });
  });
};

Answer 1

fetch 不允许您使用一个请求两次，至少在当前版本中是这样:)。在 checkResponse 和 addToCache 中使用相同的请求对象可能是这种情况。您可以在调用 fetch 之前尝试克隆请求对象，如此处所述 Why does this code fail to execute 'fetch'?