Question

I have 3 ajax call in one function and checkAjaxCompletion which checks each ajax completion flag.

What the code below does is send multiple separate ajax calls and interval method checks completion flags to determine whether to proceed or keep interval. (I know clearInterval is not shown but the point is I want to use something other than interval)

Current code is:

function manyAjax() {

   setInterval( function() { checkAjaxCompletion(); } , 200);

   ajax1(); 

   ajax2();

   ajax3();

}

function ajax1() {
   //send ajax request to server and if success set flag to 1. Default is 0. Error is 2.
}

function ajax2() {
   //send ajax request to server and if success set flag to 1. Default is 0. Error is 2.
}

function ajax3() {
   //send ajax request to server and if success set flag to 1. Default is 0. Error is 2.
}

function checkAjaxCompletion() {

   if(ajax1_flag == 1 && ajax2_flag == 1 && ajax3_flag == 1) {
       //everything went success, do some process
   }
   else if(ajax1_flag == 2 || ajax2_flag == 2 || ajax3_flag == 2) {
       //some ajax failed, do some process
   }
   else {
      //all ajax have not been completed so keep interval i.e. do nothing here
   }
}

But I’m hesitating to depend on using interval function because calling it so often seem such waste of memory. There must be better way to do. I’m thinking if observer pattern can be applied here but would like to hear opinions.

Answer 1

It is observer-notifier, if you want to call it that – but each of your ajax calls will more than likely have a callback in javascript when they complete. Why not call checkAjaxCompletion() at the end of each of them, and do nothing if you’re still waiting on others?