Loop over 2 levels in an array and log the parent and child items?

Question

I have key based arrays:

const selected = {
  1: [a, b, c],
  2: [d, e, f]
}

I need to loop over each item in the second level and also print its parent. So I need my output to be something like:

1a
1b
1c
2d
2e
3f

I havn't got very far. The following loggs the whole object but I expected it to run on '1' and '2'

Array.of(selected).forEach((item)=>{
  console.log(item)
});

Im using babel so happy to use ES6 for the solution.

Answer 1

Object.entries() is great:

 const selected = { 1: ['a', 'b', 'c'], 2: ['d', 'e', 'f'] }; Object.entries(selected).forEach(([key, value]) => { value.forEach(v => console.log(key + v)); }); 

Answer 2

All you need is Object.entries with .forEach() and a nested loop.

 const selected = { 1: ['a', 'b', 'c'], 2: ['d', 'e', 'f'] }; Object.entries(selected) .forEach(([key, arr]) => arr.forEach(v => console.log(key + v))); 

The Array.from would work instead of Array.of if you had a .length , though you'd have a sparse array.

---

 const selected = { 1: ['a', 'b', 'c'], 2: ['d', 'e', 'f'], length: 3, }; Array.from(selected) .forEach((arr, i) => arr && arr.forEach(v => console.log(i + v)));