WeekYear

WeekYear добавляет API .weekYear() для получения года по номеру недели, с учетом локали.

var weekYear = require('dayjs/plugin/weekYear'); // Зависит от плагина weekOfYear
// import weekYear from 'dayjs/plugin/weekYear' // ES 2015

var weekOfYear = require('dayjs/plugin/weekOfYear');
// import weekOfYear from 'dayjs/plugin/weekOfYear' // ES 2015

dayjs.extend(weekOfYear);
dayjs.extend(weekYear);

dayjs().weekYear();