I have this function callback function classification( $a = NULL ) { global $base_url; $awards = profile_award('1'); $n = count($awards); $items = array(); for ( $x = 0; $x < $n; $x++) { array_push($items, "<img src=\"$base_url/sites/default/files/viewer/objects/backgrounds/" . $awards[$x]['background'] . "\" width=\"75\" height=\"75/>"); } print drupal_json($items); } And when the select option change, it call this function: function refresh_award() { $.get('/classification/', function(data){ var node = JSON.decode(data); console.log( node ); // open firebug console to see the data }); }; But in firebug console I'm receiving this JSON.decode is not a function var node = JSON.decode(data); why?