Javascript, repeating an object key N-times, being N its value

Question

I was wondering how to do this in the more cleaner and optimal way:

I have an Object with the following structure:

{
   \"125\": 2,
   \"439\": 3,
           


        

Answer 1

A helper function:

function flatten(obj){
 //static Array method: create array (a elements, value b) 
 Array.aXb = Array.aXb || function(a,b){
    b = b || 0;
    return String(this(a)).split(',').map(function(){return b;});
 }
 //obj2array 
 var arr = [];
 for (var k in obj)
    if (+obj[k]) arr = arr.concat(Array.aXb(+obj[k],k));
 return arr;
}
var obj= {"125": 2,"439": 3,
          "560": 1,"999": 2 },
flatten(obj); //=> [125,125,439,439,439,560,999,999]