Immutability interview questions

Recursively freeze an object and every nested object and array, making the whole structure deeply immutable.

Implement the ES2023 change-by-copy trio — toSorted, toReversed, and with — that copy an array instead of mutating it.

Store entities flat by id, normalizing nested relations and merging updates immutably.

Build a pure, immutable reducer that opens an assistant message, appends streamed deltas, and finalizes it.

Write a reducer whose body mutates a draft, getting an immutable next state that a reducer is required to return.

Implement produce so mutating a draft proxy yields a new immutable state with structural sharing.

Apply optimistic updates immediately and roll them back on failure, even with concurrent mutations.

Build an immutable list where every update returns a new version that shares unchanged nodes with the old one — structural sharing over a cons list.