Use the Omit helper type to drop properties from a type

TypeScript 3.5 introduced an Omit helper, which allows you to exclude specific properties from an existing type. One situation where this is useful is excluding internal stuff from auto-generated types, e.g.:

// Imagine this is provided from outside:
interface InternalBook {
    _intenralId: number;
    id: string;
    name: string;

// Now we can just drop the internal stuff, while preserving type safety:
type Book = Omit<InternalBook, "_intenralId">;

// Let's test it:
const book: Book = {
    id: "1",
    name: "Life of Pi"

More information can be found here.