ip-utils/lib/module/esnext/Mask.js

Library of useful functions related to IP

import { fromLong } from './FromLong';
export function mask(subnet) {
    let split = subnet.split('/');
    let longMask = Math.pow(2, 32) - Math.pow(2, 32 - parseInt(split[1], 10));
    return fromLong(longMask);
}