Best way to create an array from an object that has number of copies

From an object like this:

{a:1, b: 2, c: 3}

I would like to turn into

['a', 'b', 'b', 'c', 'c', 'c']

Where the key is the string and the value is the number of copies, order doesn’t matter.

What’s the best way to do this?

I was thinking about using array.fill but not sure if that’s actually easier than just iterating and push.

Edit: Currently this:

const arr = []
_.each(obj, function (v, k) {
  _.times(v, function () {
    arr.push(k)
  })
})

>Solution :

You could flatMap the Object.entries and fill an array of each size.

const obj = { a: 1, b: 2, c: 3 };
const result = Object.entries(obj).flatMap(([k, v]) => Array(v).fill(k));

console.log(result)

or with Lodash

const obj = { a: 1, b: 2, c: 3 };
const arr = _.flatMap(obj, (v,k) => Array(v).fill(k))

console.log(arr);

<script src="https://cdn.jsdelivr.net/npm/lodash@4.17.21/lodash.min.js"></script>

But there’s nothing like a simple loop

const obj = { a: 1, b: 2, c: 3 };
const result = []

for (let [k, v] of Object.entries(obj)) {
  while (v--) {
    result.push(k)
  }
}

console.log(result)