“CAUTION: provisional headers are shown” in Chrome debugger

The resource could be being blocked by an extension (AdBlock in my case). The message is there because the request to retrieve that resource was never made, so the headers being shown are not the real thing. As explained in the issue you referenced, the real headers are updated when the server responds, but there … Read more

Maximum on HTTP header values?

No, HTTP does not define any limit. However most web servers do limit size of headers they accept. For example in Apache default limit is 8KB, in IIS it’s 16K. Server will return 413 Entity Too Large error if headers size exceeds that limit. Related question: How big can a user agent string get?

Set cookies for cross origin requests

Cross site approach To allow receiving & sending cookies by a CORS request successfully, do the following. Back-end (server): Set the HTTP header Access-Control-Allow-Credentials value to true. Also, make sure the HTTP headers Access-Control-Allow-Origin and Access-Control-Allow-Headers are set and not with a wildcard *. For more info on setting CORS in express js read the … Read more

What’s the point of the X-Requested-With header?

A good reason is for security – this can prevent CSRF attacks because this header cannot be added to the AJAX request cross domain without the consent of the server via CORS. Only the following headers are allowed across origins: Accept Accept-Language Content-Language Last-Event-ID Content-Type any others cause a “pre-flight” request to be issued in … Read more

Adding a HTTP header to the Angular HttpClient doesn’t send the header, why?

The instances of the new HttpHeader class are immutable objects. Invoking class methods will return a new instance as result. So basically, you need to do the following: let headers = new HttpHeaders(); headers = headers.set(‘Content-Type’, ‘application/json; charset=utf-8’); or const headers = new HttpHeaders({‘Content-Type’:’application/json; charset=utf-8′}); Update: adding multiple headers let headers = new HttpHeaders(); headers … Read more

How can I add a custom HTTP header to ajax request with js or jQuery?

There are several solutions depending on what you need… If you want to add a custom header (or set of headers) to an individual request then just add the headers property: // Request with custom header $.ajax({ url: ‘foo/bar’, headers: { ‘x-my-custom-header’: ‘some value’ } }); If you want to add a default header (or … Read more

How do I force files to open in the browser instead of downloading (PDF)?

To indicate to the browser that the file should be viewed in the browser, the HTTP response should include these headers: Content-Type: application/pdf Content-Disposition: inline; filename=”filename.pdf” To have the file downloaded rather than viewed: Content-Type: application/pdf Content-Disposition: attachment; filename=”filename.pdf” The quotes around the filename are required if the filename contains special characters such as filename[1].pdf … Read more

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