pthiers/gist:130f3ed4b04d12f286529aaed8a5b8ae

## gistfile1.html
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Worker</title>
</head>
<body>


<script type="text/js-worker">
  var factorial = function(value){
    if(value === 1 || value === 0)
      return 1;
    return value * factorial(value-1);
  };

  var id = Date.now();

  onmessage = function (oEvent) {
    switch (oEvent.data.type) {
      case 'factorial':
          var response = {
            id: id,
            type: 'factorial',
            value: factorial(oEvent.data.value)
          };
          this.postMessage(response);
        break;
      default:
        var response = {
          id: oEvent.data.id,
          type: 'default',
          value: 'default'
        };
        this.postMessage(response);
        break;
    }
  }
</script>
<script type="text/javascript">
var CONST_MAX_WORKER = 4;
var CONST_NEW_WORKER_EVENT = "Event";

var Event = document.createEvent('Event');
Event.initEvent(CONST_NEW_WORKER_EVENT, true, true);

//worker loader
var blob = new Blob(Array.prototype.map.call(
  document.querySelectorAll("script[type=\"text\/js-worker\"]"),
   function (oScript) { return oScript.textContent; }
),
{
  type: "text/javascript"
}
);

var url = window.URL.createObjectURL(blob);

var values = [];
for (var i = 0, l = 20; i < l; i++) {
    values.push(Math.round(Math.random() * l))
}

document.addEventListener(CONST_NEW_WORKER_EVENT,function(){
  var w = new Worker(url);

  w.onmessage = function(e){
      console.log(e.data);
      document.dispatchEvent(Event);
      this.terminate();
  }

  if(values.length>0){
    value = values.shift();
    w.postMessage({
      type:'factorial',
      value: value
    });
  }else{
    w.terminate();
  }
},false);


for(var i = 0;i<CONST_MAX_WORKER; i++){
  document.dispatchEvent(Event);
}
</script>
</body>
</html>
	<!DOCTYPE html>
	<html lang="en">
	<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<meta http-equiv="X-UA-Compatible" content="ie=edge">
	<title>Worker</title>
	</head>
	<body>


	<script type="text/js-worker">
	var factorial = function(value){
	if(value === 1 \|\| value === 0)
	return 1;
	return value * factorial(value-1);
	};

	var id = Date.now();

	onmessage = function (oEvent) {
	switch (oEvent.data.type) {
	case 'factorial':
	var response = {
	id: id,
	type: 'factorial',
	value: factorial(oEvent.data.value)
	};
	this.postMessage(response);
	break;
	default:
	var response = {
	id: oEvent.data.id,
	type: 'default',
	value: 'default'
	};
	this.postMessage(response);
	break;
	}
	}
	</script>
	<script type="text/javascript">
	var CONST_MAX_WORKER = 4;
	var CONST_NEW_WORKER_EVENT = "Event";

	var Event = document.createEvent('Event');
	Event.initEvent(CONST_NEW_WORKER_EVENT, true, true);

	//worker loader
	var blob = new Blob(Array.prototype.map.call(
	document.querySelectorAll("script[type=\"text\/js-worker\"]"),
	function (oScript) { return oScript.textContent; }
	),
	{
	type: "text/javascript"
	}
	);

	var url = window.URL.createObjectURL(blob);

	var values = [];
	for (var i = 0, l = 20; i < l; i++) {
	values.push(Math.round(Math.random() * l))
	}

	document.addEventListener(CONST_NEW_WORKER_EVENT,function(){
	var w = new Worker(url);

	w.onmessage = function(e){
	console.log(e.data);
	document.dispatchEvent(Event);
	this.terminate();
	}

	if(values.length>0){
	value = values.shift();
	w.postMessage({
	type:'factorial',
	value: value
	});
	}else{
	w.terminate();
	}
	},false);


	for(var i = 0;i<CONST_MAX_WORKER; i++){
	document.dispatchEvent(Event);
	}
	</script>
	</body>
	</html>