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

Whether any of these approaches is cleaner is quite subjective:

// some helper function for creating an array with repeated values
function repeat(val, times) {
    var arr = [];
    for(var i = 0; i < times; i = arr.push(val));
    return arr;
}

function convert(obj) {
    var result = [], key;
    for(key in obj) {
        result = result.concat(repeat(+key, obj[key]));
    }
    return result;
}

Or a more functional approach:

Object.keys(obj).reduce(function(result, key) {
    return result.concat(repeat(+key, obj[key]));
}, []);

// with underscore.js
_.reduce(_.keys(obj), function(result, key) {
    return result.concat(repeat(+key, obj[key]));
}, []);