javascript - create a callback function instead of using a flag var to control when a specific function is done -

i have code snipet this:

 var nbrprevart = $("#accordion > div .accordionpanel").size(); var processing = false;  if (nbrprevart == 0) {     processing = true;     getarticlespreview();//fetches articles first }  //loop makes browser wait  until finishes "getarticlespreview()"  while(!processing) { }  //getarticlespreview() finished can safely execute step $.ajax({     type: "get",     url: "http://mydomain.com/somepage.htl",     success: function(data) { alert(data);} });   //-----------------------------------  function getarticlespreview() {     //lenghty operation     processing = false; } 

don't practical because using loop make wait until function competely executed perform next step.

is there way define callback message called when first operation done , have second step ( $.ajax call) inside run properly?

thank in advance! teixeira

you create callback yourself, using apply function. juste have add callback parameter getarticlespreview, , put function inside callback.

this :

function makeajax() {     $.ajax({        type: "get",        url: "http://mydomain.com/somepage.htl",       success: function(data) { alert(data);}     }); }  function getarticlespreview(callback) {     //lenghty operation      callback.apply(this) }  var nbrprevart = $("#accordion > div .accordionpanel").size();  if (nbrprevart == 0) {     getarticlespreview(makeajax); }