Flatten Nested Array to Depth N

Problem

Implement `flat(arr, depth)` without using the built-in `Array.prototype.flat`.

Input

N/A — run a test case and print the result.

Output

JSON.stringify of the flattened result.

Constraints

depth ≥ 0, input is an array that may contain arrays at any depth.

Sample input

[1, [2, [3, [4]]]], depth=2

Sample output

[1,2,3,[4]]

Explanation

Depth-2 flatten unwraps the first two levels of nesting.

recursionarraysfunctional@Google@Meta

Visible test cases

in: [1, [2, [3, [4]]]], depth=1

out: [1,2,[3,[4]]]

in: [1, [2, [3, [4]]]], depth=Infinity

out: [1,2,3,4]

Your solution — run it, use AI if stuck

javascript