In JavaScript, when creating an array of a certain length, you can use Array.from to create an array of the desired length:

Array.from({ length: 5 }, (_, x) => x)
// => [ 0, 1, 2, 3, 4 ]

This is similar to this older idiom:

Array(5).fill().map((_, x) => x)

However, TypeScript will complain about the missing argument to fill, and you have to put in a dummy value.

Array(5).fill(0).map((_, x) => x)

However, it may confuse the reader (e.g. “what does 0 mean here?”), so now I prefer the Array.from version.