Change function with use of JavaScript function

Question

I have a website that is not mine. There are lots of JavaScript functions that make ajax calls. I wonder if there is a possibility to modify those functions so after successful ajax request my JavaScript function is called. Maybe there is possibility to inject another handler of ajax queries result codes?

Update

Maybe I should add something more... This ajax calls are realised with use of xajax library. I have found such a piece of code:

<script type="text/javascript" charset="UTF-8">
/* <![CDATA[ */
try { if (undefined == xajax.config) xajax.config = {}; } catch (e) { xajax = {}; xajax.config = {}; };
xajax.config.requestURI = "xajax_loader.php";
xajax.config.statusMessages = false;
xajax.config.waitCursor = true;
xajax.config.version = "xajax 0.5 rc1";
xajax.config.legacy = false;
xajax.config.defaultMode = "asynchronous";
xajax.config.defaultMethod = "POST";
/* ]]> */
</script>

I do not know xajax library, but maybe there is a way to add something to config so requests after success calls JavaScript functions?

You mean, so they get executed for every user of the site? Not without hacking the server, no. — Pekka, Jun 12 '13 at 07:44
No, no. Just for me - no hacking ;) I want for example to inject code that after every ajax success plays a sound or in order to make it simpler - shows alert dialog. — karex, Jun 12 '13 at 07:47
If it's just for you, you might consider a chrome extension: http://stackoverflow.com/questions/8559482/intercept-javascript-requests-with-chrome-extension — izb, Jun 12 '13 at 07:49
I want it to run on android default browser, so use of (chrome) extensions isn't an option. — karex, Jun 12 '13 at 07:52
What do you _actually_ want to achieve? Inline replacing site code is rather involved... — Koterpillar, Jun 12 '13 at 08:14
As I wrote - I want to run a javascript (which for example plays a sound) after completion of certain (or each) ajax request. — karex, Jun 12 '13 at 08:26
I guess this is what I want, but for now I do not have possibility to check it. http://community.xajax-project.org/topic/9009/how-to-get-a-success-callback-through-xajax/ Anyone can tell if it will work? — karex, Jun 12 '13 at 12:03

score 1 · Answer 1 · answered Dec 25 '13 at 02:21

It is possible to replace javascript function definitions. Here is some simple code:

<script>
   function xyz() {alert('xyz');}
</script>
<body>
    <button onclick="xyz();">Run xyz</button>
    <button onclick="alert(xyz);">Show xyz</button>
    <button onclick="xyz=function(){alert('xxxxyz');};">Replace xyz</button>
</body>

I created a fiddle http://jsfiddle.net/k565L/ to try this out. But I do not know if it is possible to replace cross-site javascript functions.

demux · Answer 2 · 2013-12-25T03:14:06.403

The source code is available here: https://github.com/Xajax/Xajax/blob/master/xajax_js/xajax_core_uncompressed.js

You might consider doing something like this:

xajax.origCompleteResponse = xajax.completeResponse;
xajax.completeResponse = function(oRequest) {
    // Here you could do anything you want.
    // For example check the request object:
    console.log(oRequest);
    // And then return a call to the original function:
    return xajax.origCompleteResponse.apply(xajax.origCompleteResponse, arguments);
};

Another way of doing the same thing:

(function() {
    var super = xajax.completeResponse; // You can use any variable name you like.
    xajax.completeResponse = function(oRequest) {
        // Here you could do anything you want.
        // For example check the request object:
        console.log(oRequest);
        // And then return a call to the original function:
        return super.apply(super, arguments);
    };
}());

See definition here: https://github.com/Xajax/Xajax/blob/master/xajax_js/xajax_core_uncompressed.js#L3666

Change function with use of JavaScript function

2 Answers2