¿Cómo añadir el número de días a la fecha de hoy?

var someDate = new Date();
var numberOfDaysToAdd = 6;
someDate.setDate(someDate.getDate() + numberOfDaysToAdd); 

var dd = someDate.getDate();
var mm = someDate.getMonth() + 1;
var y = someDate.getFullYear();

var someFormattedDate = dd + '/'+ mm + '/'+ y;

Date.prototype.addDays = function(days) {
    this.setDate(this.getDate() + parseInt(days));
    return this;
};

var currentDate = new Date();
// to add 4 days to current date
currentDate.addDays(4);