CODEWITHSUNDEEP
javascripthttp-headersxmlhttprequest
Youss
Youss

Reputation: 4212

How to set getAllResponseHeaders() on xhr object

I'm logging xhr request using this code:

(function(open) {
  XMLHttpRequest.prototype.open = function(method, url, async) {

if (..something..) 
{

...
open.call(this, method, url, async);
...

}

  };

})(XMLHttpRequest.prototype.open);

So now I would like to get the response headers eg console.log(getAllResponseHeaders()) I tried implementing it everywhere in the code but I get nothing out of it, meaning nothing is logged. Where or how do I get the response headers?

Upvotes: 1

Views: 488

Answers (1)

Paul S.
Paul S.

Reputation: 66334

Remember that the headers only exist once they've arrived, not before. This means you have to use an event listener to catch them. By state 4 they definately exist.

(function(open, headers) {
    var headhandle = function () {
        if (this.readyState === 4) console.log(headers.call(this));
    };
    XMLHttpRequest.prototype.open = function(method, url, async) {
        this.addEventListener('readystatechange', headhandle);
        open.call(this, method, url, async);
    };
}(XMLHttpRequest.prototype.open, XMLHttpRequest.prototype.getAllResponseHeaders));

var x = new XMLHttpRequest();
x.open();
x.send();
/*
Date: Tue, 31 Dec 2013 13:43:42 GMT
Content-Encoding: gzip
Vary: *
Last-Modified: Tue, 31 Dec 2013 13:43:43 GMT
X-Frame-Options: SAMEORIGIN
Content-Type: text/html; charset=utf-8
Cache-Control: public, max-age=60
Content-Length: 14317
Expires: Tue, 31 Dec 2013 13:44:43 GMT
*/

Tested with readyState === 3 and it does not give a result so you'll definitely need to wait for 4.

Upvotes: 1

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