Question

104

Overriding XMLHttpRequest.open()

rated 0 times [ 106] [ 2] / answers: 1 / hits: 26845 / 13 Years ago, sat, october 15, 2011, 12:00:00

How would I be able to override the XMLHttpRequest.open() method and then catch and alter it's arguments?

I've already tried the proxy method but it didn't work, although removing the open over-rid when XMLHttpRequest() was called:

(function() {

    var proxied = window.XMLHttpRequest.open;

    window.XMLHttpRequest.open = function() {

        $('.log').html(arguments[0]);

        return proxied.apply(this, arguments);

    };

})();

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grayson

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answered 13 Years ago nolancampbellc · Accepted Answer

You are not modifying the open method inherited by XMLHttpRequest objects but just adding a method to the XMLHttpRequest constructor which is actually never used.

I tried this code in facebook and I was able to catch the requests:

(function() {

    var proxied = window.XMLHttpRequest.prototype.open;

    window.XMLHttpRequest.prototype.open = function() {

        console.log( arguments );

        return proxied.apply(this, [].slice.call(arguments));

    };

})();



/*

    [POST, /ajax/chat/buddy_list.php?__a=1, true]

    [POST, /ajax/apps/usage_update.php?__a=1, true]

    [POST, /ajax/chat/buddy_list.php?__a=1, true]

    [POST, /ajax/canvas_ticker.php?__a=1, true]

    [POST, /ajax/canvas_ticker.php?__a=1, true]

    [POST, /ajax/chat/buddy_list.php?__a=1, true]

*/

So yeah the open method needs to be added to XMLHttpRequest prototype (window.XMLHttpRequest.prototype) not XMLHttpRequest constructor (window.XMLHttpRequest)