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JQuery $.post in a function. Wait for callback to define the return.


How would I, using $.post() in a function, force the return on the post callback?

Example:

function myFunction(){
   $.post(postURL,mydata,function(data){
      return data; 
   });
}

I have tried playing around with it using .done() and .queue() however neither has worked for me. I understand there is a fundamental flaw in my example; with that said, how can I achieve my desired functionality?


Solution

  • This is impossible. $.Ajax calls will always return immediately. You need to deal with the return when it is called through a callback (possibly several seconds later). Javascript never blocks for a given call. It may help to think of your code like this:

     //This entirely unrelated function will get called when the Ajax request completes
     var whenItsDone = function(data) {
       console.log("Got data " + data); //use the data to manipulate the page or other variables
       return data; //the return here won't be utilized
     }
    
     function myFunction(){
       $.post(postURL, mydata, whenItsDone);
     }
    

    If you're interested more on the benefits (and drawbacks) of Javascript's no-blocking, only callbacks: this Node.js presentation discusses its merits in excruciating detail.