Flatten a tree with depth in JavaScript
JavaScript interview exercise on Objects, difficulty 3 of 3. Solve it in the editor beside a worked example, or cold in Interview mode with the example hidden; the tests run the moment you do.
Write flattenTree(nodes) for an array of { name, children? } that returns a flat array of { name, depth } in depth-first order, root nodes at depth 0.
Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Interview mode hides the example: solve it from memory, without the hint or the solution, and it counts as solved cold. Progress is saved in your browser, and in your account if you sign in.