CalculationDate function: plus()

Returns a new CalculationDate relative to the CalculationDate by the number of units, which can be days, weeks, months or years, etc. 

var date = now.valueOf('2017-03-15'); // a Wednesday

var after = date.plus(1, ‘day’);

console.log('after = %s', after);

//after = 2017-03-16 00:00:00