如何更改请求的标头？

Question

是否可以更改事件Request接收的对象的标题fetch？

两次尝试:

1. 修改现有标头:

   self.addEventListener('fetch', function (event) {
     event.request.headers.set("foo", "bar");
     event.respondWith(fetch(event.request));
   });
   

   失败了Failed to execute 'set' on 'Headers': Headers are immutable.

2. 创建新Request对象:

   self.addEventListener('fetch', function (event) {
     var req = new Request(event.request, {
       headers: { "foo": "bar" }
     });
     event.respondWith(fetch(req));
   });
   

   失败了 Failed to construct 'Request': Cannot construct a Request with a Request whose mode is 'navigate' and a non-empty RequestInit.

(另请参阅如何更改响应的标头？)

Answer 1

只要设置了所有选项,就可以创建新的请求对象:

// request is event.request sent by browser here 
var req = new Request(request.url, {
    method: request.method,
    headers: request.headers,
    mode: 'same-origin', // need to set this properly
    credentials: request.credentials,
    redirect: 'manual'   // let browser handle redirects
});

您不能使用原来mode如果是navigate(这就是为什么你得到一个例外),你可能想通过重定向返回到浏览器,让它改变,而不是让它的URL fetch处理.

确保你没有在GET请求上设置body - fetch不喜欢它,但浏览器有时会在响应POST请求的重定向时与body生成GET请求.fetch不喜欢它.

Answer 2

您可以基于原始请求创建一个新请求并覆盖标头：

new Request(originalRequest, {
  headers: {
    ...originalRequest.headers,
    foo: 'bar'
  }
})

另见：https : //developer.mozilla.org/en-US/docs/Web/API/Request/Request

Answer 3

您是否尝试过类似于您提到的问题中的解决方案(如何更改响应的标头？)？

在Service Worker Cookbook中,我们手动复制Request对象以将它们存储在IndexedDB中(https://serviceworke.rs/request-deferrer_service-worker_doc.html).这是出于不同的原因(我们希望将它们存储在缓存中,但由于https://github.com/slightlyoff/ServiceWorker/issues/693我们无法存储POST请求),但它应该适用于您的内容我也想做.

// Serialize is a little bit convolved due to headers is not a simple object.
function serialize(request) {
  var headers = {};
  // `for(... of ...)` is ES6 notation but current browsers supporting SW, support this
  // notation as well and this is the only way of retrieving all the headers.
  for (var entry of request.headers.entries()) {
    headers[entry[0]] = entry[1];
  }
  var serialized = {
    url: request.url,
    headers: headers,
    method: request.method,
    mode: request.mode,
    credentials: request.credentials,
    cache: request.cache,
    redirect: request.redirect,
    referrer: request.referrer
  };



  // Only if method is not `GET` or `HEAD` is the request allowed to have body.
  if (request.method !== 'GET' && request.method !== 'HEAD') {
    return request.clone().text().then(function(body) {
      serialized.body = body;
      return Promise.resolve(serialized);
    });
  }
  return Promise.resolve(serialized);
}

// Compared, deserialize is pretty simple.
function deserialize(data) {
  return Promise.resolve(new Request(data.url, data));
}