What <ShippingFormInputs> actually does

useForm<ShippingFormInputs>()

This is NOT runtime code.

It only tells TypeScript:

“This form should only accept fields defined in ShippingFormInputs.”

---

📦 Example type

type ShippingFormInputs = {
  email: string;
  age: number;
};

So valid fields are only:

• "email"
• "age"

---

❌ How it catches typos

Example mistake:

register("emial"); // ❌ typo

👉 TypeScript immediately checks:

“Is 'emial' a key in ShippingFormInputs?”

Answer:

• ❌ NO

So it shows error:

Argument of type '"emial"' is not assignable to parameter of type '"email" | "age"'