Get the start date and end date from a weekString ('2021-W01')

datesFromWeek.js

/**
 * <input type=week genererar en sträng typ '2022-W12' som vi vill ha omvandlad till två datum
 * @param {string} weekString:'2021-W01'
 * @returns {object} {from: date, to: date}
 */
export const datesFromWeek = (weekString) => {
    let [y, w] = weekString.split('-')
    w = w.replace('W', '')
    const offsetDate = new Date(y, 0, w * 7)
    return {
        from: new Date(offsetDate.setDate(offsetDate.getDate() - offsetDate.getDay() + 1)),
        to: new Date(offsetDate.setDate(offsetDate.getDate() + 7 - offsetDate.getDay()))
    }
}