How to Make All Properties of a TypeScript Type Required?

To make all properties of an existing TypeScript type required, starting with TypeScript 2.8, you can simply use the Required utility type, which has the following syntax:

// TypeScript 2.8+
Required<Type>

This would strip the ? modifiers from all properties of a type, making them all required.

For example, you can use the Required utility type in the following way:

// TypeScript 2.8+
interface Foo {
    bar?: string;
    baz?: number;
    qux?: boolean;
}

type RequiredFoo = Required<Foo>;

You could use this type in the following way:

const foo: RequiredFoo = { bar: 'abc', baz: 123, qux: false };

If any of the required types are missing, it will throw an error, like in the following case:

// TypeScript 2.8+
// Error: Property 'qux' is missing in type '{ bar: string; baz: number; }' but required in type 'Required<Foo>'.
const foo: RequiredFoo = { bar: 'abc', baz: 123 };