在CORS请求上访问响应头

Question

I'm using the fetch API to make a cross-domain request similar to the below snippet

 window.fetch('http://data.test.wikibus.org/magazines', { method: 'get'}) .then(function(response) { var linkHeader = response.headers.get('Link'); document.querySelector('#link-header').innerText = 'The Link header is: ' + linkHeader; }); 

 <span id="link-header"></span> 

As you see the Link header (and some other headers too) is not accessible although it is returned in the response. I assume that's a CORS issue, because on local requests all headers are accessible.

Is that by design? Is there a way around that problem?

Answer 1

The resource you are requesting most likely lacks a Access-Control-Expose-Headers header that contains Link as value.

See https://fetch.spec.whatwg.org/#http-access-control-expose-headers and see https://fetch.spec.whatwg.org/#concept-filtered-response-cors for the details of which headers get filtered out of a CORS response.