“JavaScript arr.flat” Ответ

JavaScript arr.flat

The flat() method creates a new array with
all sub-array elements concatenated into it
recursively up to the specified depth.
const arr1 = [0, 1, 2, [3, 4]];

console.log(arr1.flat());
// expected output: [0, 1, 2, 3, 4]

const arr2 = [0, 1, 2, [[[3, 4]]]];

console.log(arr2.flat(2));
// expected output: [0, 1, 2, [3, 4]]