javascriptOtherMedium

Deeply nested arrays not flattening

Time: 0:00

What it should do

flattenDeep(arr) should flatten a nested array completely, however many levels deep it goes.

What goes wrong

flattenDeep([1, [2, [3, [4]]]]) returns [1, 2, [3, [4]]] — still nested.

Hints

This is a mutation and copying bugs bug

Assignment does not copy, a shallow copy still shares its contents, and mutating methods return None.