javascript - Prepare SQL - AJAX return Data -

i need setting db marker retrieval. got bit confused on pass back. here have far:

data returned:

["chatswood nsw au","chippendale nsw au"] 

js:

var opdata = [];     function markers() {             $.post("id.php", {id: <?php echo $id; ?>})             .done(function(data) {                 //data array returned                 opdata = data; //tried                 $(opdata) = data; //tried                 opdata.push(data); //tried                 $.each(data, function(i) { //tried                     opdata.push(data[i]);                 });             });             console.log(opdata); //shows [] empty array regardless         } 

php:

$arr = array(); while (  $selectdata -> fetch() ) {     $arr[] = $address; } echo json_encode($arr); 

how go retrieving data? none of above working.

this driving me nuts.. should $.ajax instead?

the call .done asynchronous, meaning .done finishes right away, before ajax call made, , console.log called right after, if http call not finished yet.

based on use case , context can choose between 3 options return opdata caller function:

///// option 1: synchronous call function markersusingsynchronouscalltoajax() {     var opdata = [];     $.ajax({         type: "post",         url: "id.php",         async: false, // disable asynchronous call ajax         data: {id: <?php echo $id; ?>},         success: function(data) {             opdata = data;         }     })     return opdata; } var opdata = markersusingsynchronouscalltoajax(); console.log("using synchronous ajax call", opdata);   ///// option 2: callback  function markersusingcallback(callback) {     $.post("id.php", {id: <?php echo $id; ?>})     .done(function(data) {         callback(data);     }); } markersusingcallback(function(opdata){     console.log("using callback", opdata); });    ///// option 3: promise  function markersusingpromise(callback) {     return $.post("id.php", {id: <?php echo $id; ?>}); } markersusingpromise().done(function(opdata){     console.log("using promise", opdata); });