30-seconds-of-code/js/snippets/complement.md

title, type, tags, cover, dateModified

title	type	tags	cover	dateModified
Logical complement	snippet	function logic	flower-portrait-10	2020-09-15T16:28:04+03:00

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.

const complement = fn => (...args) => !fn(...args);

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