How to set the same value on multiple keys

Question

How is it possible to set the same value on multiple keys? For example I have the following object:

const obj = {
   a: 5,
   b: 5,
   c: 5,
   d: 6
}

Is there any easy way for example lets say I have array of [a, b, c] (keys) and to spread them in object and set them as keys with same value. Point is to look more classy for example:

const keys =[a, b, c]
const obj = {
  [...keys]: 5
}

I know this would throw error but looking for some shorthand to achieve this

Answer 1

Take the array of keys and map each to an entry of the key and the 5 value:

const keys = ['a', 'b', 'c'];
const obj = {
  ...Object.fromEntries(
    keys.map(key => [key, 5])
  ),
  d: 6
};

console.log(obj);

Answer 2

Something like this works:

const obj = {};
const value = 5;
['a', 'b', 'c'].forEach(key => obj[key] = value);