Adds a year to the current year.

add-year.js

/**
 * @param {string} currentDate - The current date.
 * @returns {string} Returns the new expiration date.
 */
private addYear = (currentDate: string): string => {
    // Add a day to the current date.
    let objDate = new Date(currentDate);
    objDate.setDate(objDate.getDate() + 1);

    // Format the month.
    let numMonth = objDate.getMonth() + 1;
    let strMonth = numMonth.toString();
    if (numMonth < 10) { strMonth = "0" + numMonth; }

    // Format the day.
    let numDay = objDate.getDate();
    let strDay = numDay.toString();
    if (numDay < 10) { strDay = "0" + numDay; }

    // Add a year to the current date.
    let newExpiration = 
        (objDate.getFullYear() + 1).toString() + "-" +
        strMonth + "-" +
        strDay
    ; // strInvoiceNum

    return newExpiration;
} // addYear(currentDate)