Javascript - Callbacks

var maxSeconds = 5;

var myDoubler = function(myNumber, myCallback){
    var calculationTime = Math.floor(Math.random()*(maxSeconds * 1000));

    if(myNumber%2){
        setTimeout(function(){
            myCallback(new Error("Odd number"));
        }, calculationTime);
    }else{
        setTimeout(function(){
            myCallback(null, myNumber*2, calculationTime);
        }, calculationTime);
    }
};

for (var i = 0; i < 10; i++) {
    myDoubler(i, function(err, results, time){
    if(err) {
        console.log("Error: " + err.message);
    }
    else{
        console.log("The result: " + results + "  " + time );
    }
});
}

// OR WITH A SEPARATE HANDLE FUNCTION

 var myResultHandler = function(err, results, time){
     if(err) {
         console.log("Error: " + err.message);
     }
     else{
         console.log("The result: " + results + "  " + time );
     }
 };

 for (var i = 0; i < 10; i++) {
     myDoubler(i, myResultHandler);
 }