Lesson 5 / 28

any & unknown

Compare any and unknown, and learn why unknown with narrowing is the safer choice for API and JSON data.

any: the escape hatch

any turns off type checking for that value completely. It compiles, but you've thrown away TypeScript's whole point.

unknown: the safer any

unknown accepts anything too, but you must narrow it before using it — TS forces a check first.

let data: unknown = JSON.parse('"hello"');
data.toUpperCase();
// Error: 'data' is of type 'unknown'.

if (typeof data === "string") {
  data.toUpperCase(); // OK, narrowed to string
}

Prefer unknown over any

For truly unpredictable data (API responses, JSON), reach for unknown and narrow it — keep any only as a last resort.