What are typeof and instanceof in TypeScript, and how are they used?

typeof and instanceof are operators used in TypeScript (and JavaScript) to check types, but they work differently.

• typeof returns a string describing the primitive type of a value (e.g., "string", "number", "boolean", "undefined", "object", "function"). It is used for checking primitive types.

const value = "hello";
if (typeof value === "string") {
  // value is a string
}

• instanceof checks whether an object is an instance of a specific class or constructor. It works with objects and classes.

class User {}
const user = new User();
if (user instanceof User) {
  // user is an instance of User
}

In TypeScript, these operators are often used for type narrowing in conditional statements, so the compiler understands the specific type of a variable and allows safe access to its properties.