Mapped typed to make all properties required

Question

A TypeScript class can have optional properties and required properties.

class SomeClass {
  foo?: string;
  bar?: string;
  baz: string = '';
  qux: string = '';
}

The Partial<T> mapped type can make all the properties optional.

type SomeClassPartial = Partial<SomeClass>;

The question is, can we go the opposite way and make all the properties required?

type SomeClassComplete = Complete<SomeClass>;

The Partial mapped type adds a ? to all the properties, thereby making them all optional. What I am looking for is a way to remove the ? from all the properties, thereby making them all required.

We tried using the ! operator but it is doesn't have that semantic.

type Complete<T> = {
  [P in keyof T]: T[P];
};

Answer 1

Found it. The Required<T> partial does this.

The definition is inside TypeScript/lib.es5.d.ts here.

/**
 * Make all properties in T required
 */
type Required<T> = {
    [P in keyof T]-?: T[P];
};