如何从 fetch 中获取响应的标头

Question

I am using fetch on chrome Version 52.0.2743.82 (64-bit). I want to get all the headers in the response. Following snippet only return content-type but if you peek into chrome dev tools it shows many other response headers. How to get other headers from fetch.

  fetch('https://httpbin.org/get')
    .then(response => {
       const headers = response.headers.entries();
       let header = headers.next();
       while (!header.done){
         console.log(headers.value);
         header = header.next();
       }
    })

I tried polyfilling(manually overriding) the github implementation. Still no luck.

Answer 1

You can't access all the headers when requesting cross-domain content via ajax. You can access all headers if origin is same.

As explained in W3 Specifications here , only Content-Type , Last-modified , Content-Language , Cache-Control , Expires , Pragma headers are accessible.

Further https://httpbin.org/get send only Content-Type header from list of accessible headers so, you got that only.

Edit: You can expose non-standard CORS response headers by sending Access-Control-Expose-Headers with the headers you want the client to access on the response.