How to make a random array of 40 unique elements?

Question

JavaScript

At first I thought that it was possible to shove a randomized array into a set, but I did not understand how to get a specific number of elements at the output.

Answer 1

At first I thought that it was possible to shove a randomized array into a set ...

It should be the other way around - first set, then array:

const set = new Set;
while (set.size < 40) {
  set.add(Math.random() * 100 | 0);
}
const arr = [...set];