// source http://jsbin.com/vopahof

index.html

<script src="https://code.jquery.com/jquery-3.1.0.js"></script>
<script src="https://gist.githubusercontent.com/tnngo2/9c27c8aa5c91b9f13f6f93fd46dd94c2/raw/3f3b641cada3fc069dc77e12cfc3467bd0b75adb/jsbin.vopahof.js"></script>
<script id="jsbin-javascript">
function execCallAsync () {
  console.log('exeCallAsync:start');
  callAsync();
  sleep(9000);
  console.log('exeCallAsync:end');
}


function execExecCallAsync () {
  console.log('execExecCallAsync:start');
  execCallAsync();
  sleep(5000);
  console.log('execExecCallAsync:end');
}

function execExecExecCallAsync () {
  console.log('execExecExecCallAsync:start');
  execExecCallAsync();
  console.log('execExecExecCallAsync:end');
}


execExecExecCallAsync();
</script>


<script id="jsbin-source-javascript" type="text/javascript">function execCallAsync () {
  console.log('exeCallAsync:start');
  callAsync();
  sleep(9000);
  console.log('exeCallAsync:end');
}


function execExecCallAsync () {
  console.log('execExecCallAsync:start');
  execCallAsync();
  sleep(5000);
  console.log('execExecCallAsync:end');
}

function execExecExecCallAsync () {
  console.log('execExecExecCallAsync:start');
  execExecCallAsync();
  console.log('execExecExecCallAsync:end');
}


execExecExecCallAsync();</script>

jsbin.vopahof.js

function execCallAsync () {
  console.log('exeCallAsync:start');
  callAsync();
  sleep(9000);
  console.log('exeCallAsync:end');
}


function execExecCallAsync () {
  console.log('execExecCallAsync:start');
  execCallAsync();
  sleep(5000);
  console.log('execExecCallAsync:end');
}

function execExecExecCallAsync () {
  console.log('execExecExecCallAsync:start');
  execExecCallAsync();
  console.log('execExecExecCallAsync:end');
}


execExecExecCallAsync();