CODEWITHSUNDEEP
javascriptjquerycallback
DOfficial
DOfficial

Reputation: 465

Javascript / jQuery make function wait for callback before continuing

I need to know how to make a function wait for a callback from another function before executing. Below is a simplified scenario of what I am trying to accomplish.

function a(){
  b();
  // Wait for function c to callback
  var callback = function();
  // then continue function a() logic...
}
function b(){
  c();
  return false;
}

function c(){
  //trigger callback in function a
    callback();
}

Upvotes: 0

Views: 490

Answers (2)

Arun P Johny
Arun P Johny

Reputation: 388446

What you need to do is to pass a callback to b and c as shown below and call the callback in c after its execution... assuming c is doing an async operation. 

function a() {
  snippet.log('inside a');
  b(function() {
    //code that should be executed after `c` must be here... note that you cannot return a value from here to the caller of `a`
    snippet.log('inside callback');
  });
  snippet.log('after b')
}

function b(callback) {
  snippet.log('inside b');
  c(callback);
  return false;
}

function c(callback) {
  snippet.log('inside c');
  setTimeout(function() {
    snippet.log('inside async timeout');
    //trigger callback in function a
    callback();
  }, 100);
}

a();
<!-- Provides the `snippet` object, see http://meta.stackexchange.com/a/242144/134069 -->
<script src="http://tjcrowder.github.io/simple-snippets-console/snippet.js"></script>

Upvotes: 1

Joseph Young
Joseph Young

Reputation: 2785

Put the rest of a's logic into the callback, and if you need, use a reference to a's this

function a(){
  b();
  var that = this;
  var callback = function(){
    that.variables
    // then continue function a() logic...
  }
}
function b(){
  c();
  return false;
}

function c(){
  //trigger callback in function a
    callback();
}

Upvotes: 1

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