Jquery .post() return array <p>Sorry for the bad title, but I don't know how to name this. My problem is that whenever I pass a value from a select box I trigger this jquery event in order to check on the check boxes. Bassically I echo $res[]; at selecctedgr.php. Do I need to use json? and how can I do this?</p> <p>Mainpage:</p> <pre><code>$("#group_name").change(function(){ var groupname = $("#group_name").val(); var selectedGroup = 'gr_name='+ groupname; $.post("selectedgr.php", {data: selectedGroup}, function(data){ $.each(data, function(){ $("#" + this).attr("checked","checked"); }); },"json"); }); </code></pre> <p>PHP (selectedgr.php):</p> <pre><code>&lt;?php include_once '../include/lib.php'; $gr_name=mysql_real_escape_string($_POST['gr_name']); $sqlgr = "SELECT * FROM PRIVILLAGE WHERE MAINGR_ID=".$gr_name; $resultgr = sql($sqlgr); while($rowgr = mysql_fetch_array($resultgr)){ $res[] = $rowgr['ACT_ID']; } echo $res[]; ?&gt; </code></pre>