如果服务器响应特定的东西，则运行（JS）函数

On one of my pages I have "tracking.php" that makes a request to another server, and if tracking is sucessful in Firebug Net panel I see the response trackingFinished();

Is there an easy way (built-in function) to accomplish something like this:

If ("tracking.php" responded "trackingFinished();") { *redirect*... }

Javascript? PHP? Anything?

The thing is, this "tracking.php" also creates browser and flash cookies (and then responds with trackingfinished(); when they're created). I had a JS that did something like this:

If ("MyCookie" is created) { *redirect*... }

It worked, but if you had MyCookie in your browser from before, it just redirected before "track.php" had the time to create new cookies, so old cookies didn't get overwritten (which I'm trying to accomplish) before the redirection...

The solution I have in mind is to redirect after trackingFinished(); was responded...

I think the better form in javascript to make request from one page to another, without leaving the first is with the ajax method, and this one jQuery make it so easy, you only have to use the ajax function, and pass a little parameters:

$.post(url, {parameter1: parameter1value, param2: param2value})

And you can concatenate some actions:

$.post().done(function(){}).fail(function(){})

And isntead of the ajax, you can use the $.post that is more easy, and use the done and fail method to evaluate the succes of the information recived

As mentioned above, AJAX is the best way to communicate between pages like this. Here's an example of an AJAX request to your track.php page. It uses the success function to see if track.php returned 'trackingFinished();'. If it did then it redirects the page 'redirect.php':

$.ajax({
    url: "track.php",
    dataType: "text",
    success: function(data){
        if(data === 'trackingFinished();'){
            document.location = 'redirect.php';
        }
    }
});

The example uses JQuery.