Angular8 充满了 HttpClient 响应头

Question

I'm using HttpClient to request a json file. I want the file can be cached with ETag . But it not works. I think that The If-None-Match not send to the server is the reason. So I want to get The 'ETag' from response headers. But the response header not has the item in Angular, But It's truly in the HTTP response in chrome network tool. All of showing in follow images.

How can I get the ETag from response Header

Answer 1

I think it's similar to this : HttpClient dont return all headers .

You need to setup your backend to return Access-Control-Expose-Headers:ETag .

Answer 2

As the MDN shows the cors hide lots of headers, So I can't get the ETag in angular.

Add Access-Control-Expose-Headers:ETag to response header can solve this issue.