Question

Wrox Profesionnal Javascript p188
I don’t understand this part at line 8 where the anonymous function already have an argument of num, but how can (i) is copied into the argument num. Normally a function would stop at the closing bracket }, adding (i) doesn’t make sense for me.

function createFunctions(){
    var result = new Array();
    for (var i=0; i < 10; i++){
       result[i] = function(num){
         return function(){
           return num;
         };
       }(i);
    }
    return result;
}

Answer 1

This is short hand for calling the function and passing it the parameter i. It’s like doing this:

function createFunctions(){
    var result = new Array();
    for (var i=0; i < 10; i++){
        result[i] = myFunction(i);
    }
    return result;
}

function myFunction(num){
    return function(){
        return num;
    }
}

Thinking of myFunction as the anonymous function my help you understand what’s going on, so instead of myFunction(i) you have function(num){…}(i);