jQuery ajax request proxy

How I can do the following operation with jQuery:

1. Some library send ajax request via $.ajax
2. I need to catch all these requests, a开发者_JS百科nd in some cases abort them, and instead pass off another data.

I found, that in jQuery 1.5 there were introduced new methods, such as ajaxPrefilter and ajaxTransport. I also tried ajaxSetup with beforeSend, but I can't achieve 2 points of these working...

Don't use this unless until you are damn sure about what you are doing

I am not sure about the ajax intercepter libraries. But i can tell you the nasty hack

• Take copy of your original jquery ajax instance

        var oldAjaxInstance; //some global variable
        oldAjaxInstance = $.ajax;  //in document load
  

• And assign your intercepert method to the $.ajax pointer

        $.ajax = myAjaxwrapper;
  

myAjaxwrapper looks womething like this

function myAjaxwrapper(a) {
     //your logic to change the request data's
     if (you are ok to allow the ajax call) {
         //re Assgin the actual instance of jquery ajax
         $.ajax =oldAjaxInstance;           
         //and call the method
         $.ajax(a);
     }
     //Otherwise it wont be called
}

• And onsucess of your ajax call reassign your ajax wrapper to jquery ajax

             oldAjaxInstance = $.ajax;  
             $.ajax = myAjaxwrapper;
  

Strange, but it works only in couple with two methods :)

function enableFakeAjax(isEnable, fakeData) {
  isFakeAjax = isEnable;

  $.ajaxPrefilter(function(options, originalOptions, jqXHR) {
    if (isFakeAjax) {
      jqXHR.abort();

      originalOptions.success(fakeData);
    }
  });

  $.ajaxSetup({
    beforeSend: function(jqXHR, settings) {
      if (isFakeAjax) {
        jqXHR.abort();
      }
    }
  });
}


enableFakeAjax(true, jsonData);
isFakeAjax = false;

OK, this issue was fixed in jQuery 1.5.1.