Add number of days to given date.

addDays.js

/**
 * Add the specified number of days to the date provided.
 */
var addDays = (date, days) => {
    var newDate = new Date(date);
    newDate.setDate(newDate.getDate() + days);
    return newDate;
}

// example:
var now = new Date();
var nextWeek = addDays(now, 7);

console.info('now: ', now);
console.info('next week: ', nextWeek);