jQuery AJAX cross domain

Use JSONP.

jQuery:

$.ajax({
     url:"testserver.php",
     dataType: 'jsonp', // Notice! JSONP <-- P (lowercase)
     success:function(json){
         // do stuff with json (in this case an array)
         alert("Success");
     },
     error:function(){
         alert("Error");
     }      
});

PHP:

<?php
$arr = array("element1","element2",array("element31","element32"));
$arr['name'] = "response";
echo $_GET['callback']."(".json_encode($arr).");";
?>

The echo might be wrong, it’s been a while since I’ve used php. In any case you need to output callbackName('jsonString') notice the quotes. jQuery will pass it’s own callback name, so you need to get that from the GET params.

And as Stefan Kendall posted, $.getJSON() is a shorthand method, but then you need to append 'callback=?' to the url as GET parameter (yes, value is ?, jQuery replaces this with its own generated callback method).