Create React App 2.0: Babel 7, Sass, and More(reactjs.org)

  type Keys<T> = keyof T
  type Values<T> = T[keyof T]
  type Readonly_<T> = Readonly<T>
  type Shape<T> = Partial<T>
  type NonMaybeType<T> = NonNullable<T>

  // Exact<T> cannot be implemented because TS doesn't have exact types as a separate concept,
  // It should be noted that object literals are exact by-default if there's a type annotation
  // Issue: https://github.com/Microsoft/TypeScript/issues/12936

  type Diff<A, B> = Pick<A, Exclude<keyof A, keyof B>>
  // Rest<T> should be equal to Diff, because TS doesn't have exact types

  type ElementType<T, K extends keyof T> = T[K]
  // PropertyType in unnecessary, because T[K] works for everything

  // Note that this is variadic - "Args" is an array of arguments
  type Call<F, Args extends any[]> = F extends (...args: Args) => infer B ? B : never

  // This works for both objects and tuples.
  type ObjMap<T, F> = { [K in keyof T]: Call<F, [T[K]]> }

  // I couldn't figure out how to implement Class<T>, but you can access the type of a class instance with
  // typeof ClassName.prototype 

  // $SuperType and $Subtype are not documented, so I can't try to replicate them.

  // TypeScript doesn't have existential types, but you can emulate them within the type system, or avoid them using e.g "infer"
  // Discussion and encoding https://github.com/Microsoft/TypeScript/issues/14466#issuecomment-338045331