complement

Returns a function that is the logical complement of the given function, fn.

Use the logical not (!) operator on the result of calling fn with any supplied args.

typescript

type Func<T> = (...args: T[]) => any;
const complement =
  (fn: Func<any>) =>
  (...args: any[]) =>
    !fn(...args);

typescript

const isEven = (num: number) => num % 2 === 0;
const isOdd = complement(isEven);
isOdd(2); // false
isOdd(3); // true