Question

I am trying to use jQuery to make a synchronous AJAX post to a server, and get a JSON response back.

I want to set a javascript variable msg upon successful return

This is what my code looks like:

$(document).ready(function(){
    $('#test').click(function(){
    alert('called!');
    jQuery.ajax({
      async: false,
      type: 'POST',
      url: 'http://www.example.com',
      data: 'id1=1&id2=2,&id3=3',
      dataType: 'json',
      success: function(data){ msg = data.msg; },
      error: function(xrq, status, et){alert('foobar\'d!');}
     });
});

[Edit]

I was accidentally mixing PHP and Javascript in my previous xode (now corrected). However, I now get this even more cryptic error message:

uncaught exception: [Exception… “Component returned failure code: 0x80070057 (NS_ERROR_ILLEGAL_VALUE) [nsIXMLHttpRequest.open]” nsresult: “0x80070057 (NS_ERROR_ILLEGAL_VALUE)” location: “JS frame :: http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js :: anonymous :: line 19″ data: no]

What the … ?

Answer 1

In your success callback, you are mixing Javascript and PHP code ; which is probably not quite what you want to do.

You must be aware that :

• PHP is executed on the server-side ; for .php files
• Javascript is executed on the client-side (browser)

The function hooked on the success callback will only be executed on the client-side, where there is no PHP execution ; and it will receive the data sent by the PHP script on the server-side (The one receiving the Ajax request).

The data as received by the function hooked on success is a Javascript object.

Which means that, here, you might want to use something like this :

success: function(data){ msg = data.msg; },

i.e. no PHP code here.

---

Edit after the comment + edit of the OP

You are getting a “NS_ERROR_ILLEGAL_VALUE nsIXMLHttpRequest.open” error ; which means, I suppose, that you are passing some kind of illegal URL to the Ajax request.

Are you sure that the URL you’re passing to jQuery.ajax is a valid one ?

For instance :

• It should not be empty
• It should point to an URL that’s on the same domain-name as your application