IsLeapYear
IsLeapYear adds .isLeapYear API to returns a boolean indicating whether the Dayjs's year is a leap year or not.
javascript
var isLeapYear = require('dayjs/plugin/isLeapYear');
// import isLeapYear from 'dayjs/plugin/isLeapYear' // ES 2015
dayjs.extend(isLeapYear);
dayjs('2000-01-01').isLeapYear(); // true