dolvik/index.html

## index.html
<!DOCTYPE html>
<html>
<head>
<meta name="description" content="Call any function just once within a period of time">
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>JS Bin</title>
</head>
<body>
  <input type="button" value="Call function 3 times" onclick="onClick()">
</body>
</html>

## index.js
var period = 1000;
var n = 2; //max number of functions executiong within a period

//function decorator
function getFunction(context){
  return function(func){
    var running = 0;
    return function(){
      if (running === n){
        console.log(running + " functions are running. Only " + n + " functions can run at the same time. Cancel excecution");
        return;
      }
      running++;
      func.apply(context, arguments);
      setTimeout(function(){
        running--;
      }, period);
    };
  };
}

//function that takes much time
function getData(filter, callback){
  console.log("Call function with argument filter = " +  filter);
  setTimeout(function(){
    callback(null, {data: [1, 2, 3]});
  }, 500);
}

//create a wrapper
var wrapper = getFunction(this)(getData);

//call this function 3 times when button is clicked
function onClick(){
  var filter = "some filter";
  var callback = function(err, result){
    if (err){
      console.log("Error: " + err);
      return;
    }
    console.log("Function is complete. Result = " + JSON.stringify(result));
  };
  wrapper(filter, callback);
  wrapper(filter, callback);
  wrapper(filter, callback);
}
	<!DOCTYPE html>
	<html>
	<head>
	<meta name="description" content="Call any function just once within a period of time">
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width">
	<title>JS Bin</title>
	</head>
	<body>
	<input type="button" value="Call function 3 times" onclick="onClick()">
	</body>
	</html>
	var period = 1000;
	var n = 2; //max number of functions executiong within a period

	//function decorator
	function getFunction(context){
	return function(func){
	var running = 0;
	return function(){
	if (running === n){
	console.log(running + " functions are running. Only " + n + " functions can run at the same time. Cancel excecution");
	return;
	}
	running++;
	func.apply(context, arguments);
	setTimeout(function(){
	running--;
	}, period);
	};
	};
	}

	//function that takes much time
	function getData(filter, callback){
	console.log("Call function with argument filter = " + filter);
	setTimeout(function(){
	callback(null, {data: [1, 2, 3]});
	}, 500);
	}

	//create a wrapper
	var wrapper = getFunction(this)(getData);

	//call this function 3 times when button is clicked
	function onClick(){
	var filter = "some filter";
	var callback = function(err, result){
	if (err){
	console.log("Error: " + err);
	return;
	}
	console.log("Function is complete. Result = " + JSON.stringify(result));
	};
	wrapper(filter, callback);
	wrapper(filter, callback);
	wrapper(filter, callback);
	}