Next.js: Dynamic и catch-all routes — типичные gotcha на собеседовании

Optional vs required catch-all, async params в Next 15, params always strings.

Разбор

• Catch-all vs optional. [...slug] не матчит base; [[...slug]] матчит. 404 на /docs при working /docs/x — нужны double brackets.
• params async в Next 15. Sync destructure — bug; must await params. Frequent migration break.
• Params always strings. /items/007 → '007'; compare to number silently fails.
• Route conflicts by specificity — static /shop/new beats dynamic /shop/[id]. Two dynamic siblings same level — error.
• notFound() и redirect() — idiomatic escape hatches; throw и unwind, code after never runs.

Итог

Dynamic routing gotchas: [[...slug]], await params, string comparison.