any and unknown

When you don't know the type

Data from the internet or a user could be anything. TypeScript has two types for "I don't know": any turns checking off, while unknown keeps you safe by making you check first.

any vs unknown

let a: any = "hello";
a.toFixed(2);

let u: unknown = "hello";
u.toUpperCase();

if (typeof u === "string") {
  console.log(u.toUpperCase());
}

Treat any as a last resort. Reach for unknown and check — your future self will thank you.

When you don't know the type

any vs unknown

The rest of this lesson