Loop function to determine the loop type by the object passed in. Set - (Array/Object), fn - (function to call on each iteration), order - (if order doesn't matter and set is an array, then use a while loop)

loop-function.js

function loop(set, fn, order){
    var is_array = Object.prototype.toString.call(set) === '[object Array]',
        i, l;

    if(is_array){
        l = set.length;       
        if (!order) { 
            while(l--){ fn(l); } 
        } 
        else { 
            for(i=0;i<l;i++){ fn(i) } 
        }
    } else {
        for(i in set){
            if(set.hasOwnProperty(i)){
                fn(i);
            }
        }
    }  
}