negate

Creates a function that negates the result of predicate.

Available since v2.0.0

Import

import { negate } from '@helpers4/function';
// or, from the all-in-one package (same code, one install):
import { negate } from 'helpers4/function';

negate<T extends unknown[]>(predicate: function): function

Parameter	Type	Description
`predicate`	`function`	A predicate function returning a boolean.

function — A new function that returns the logical negation of predicate.

Returns a function that inverts the boolean result of the given predicate.

const isEven = (n: number) => n % 2 === 0;
const isOdd = negate(isEven);
isOdd(3); // => true
isOdd(4); // => false

negate is ideal for inverting predicates passed to Array.filter.

const isEmpty = (arr: unknown[]) => arr.length === 0;
[[], [1], [], [2, 3]].filter(negate(isEmpty))
// => [[1], [2, 3]]