Readonly<Type>

Constructs a type with all properties of Type set to readonly, meaning the properties of the constructed type cannot be reassigned.

Example:

interface Todo {
  title: string;
}

const todo: Readonly<Todo> = {
  title: "Delete inactive users",
};

todo.title = "Hello"; // Cannot assign to 'title' because it is a read-only property.

This utility is useful for representing assignment expressions that will fail at runtime (i.e. when attempting to reassign properties of a frozen object).