Usage

Import the extensions part as early as possible to make sure the global Object Prototypes are extended.
Your IDE might offer the typing without importing this init function as they are declared globally.
Date Extensions are using dayjs internally.

import { initDateExtensions } from '@oardi/ts-utils';
initDateExtensions();

add

const date = new Date();
date.add(15, 'minutes');

diff

const startDate = new Date();
const endDate = new Date();
startDate.diff(endDate);

isAfter

const startDate = new Date();
const endDate = new Date();
startDate.isAfter(endDate);

isBefore

const startDate = new Date();
const endDate = new Date();
startDate.isBefore(endDate);