jQuery getJSON to external PHP page
It could be that you haven't got a callback in test.php. Also, json_encode only accepts an array:
$results = array("key" => "value");echo $_GET['callback'] . '(' . json_encode($results) . ')';// the callback stuff is only needed if you're requesting from different domainsjQuery automatically switches to JSONP (i.e. using script tags instead of XMLHttpRequest) when you use http://. If you have test.html and test.php on the same domain, try using relative paths (and no callbacks).
The simplest solution would be to add the below code before any output to your test.php file, then you have more flexibility with what methods you use, a standard ajax call should work.
header ('Access-Control-Allow-Origin: *');However, use the json callback thing when your getting data from a server beyond your control.