json_encode pass php array to javascript

in php i got this:

$shipping_part_list_array = $db_obj->getArticleList($elements);

 
and like this i want to pass it to javascript varriable:

var array = <?php echo  json_encode($shipping_part_list_array); ?>;

 
but my array variable is just empty. I looked a trought a lot of questions, it seems right but it just wont work. Thank you.