Moment.js
Install moment.js from here.
npm : $ npm i --save moment
Bower : $ bower install --save moment
Next,
var date = moment()
.add(2,'d') //replace 2 with number of days you want to add
.toDate(); //convert it to a Javascript Date Object if you like
Link Ref : http://momentjs.com/docs/#/manipulating/add/
Moment.js is an amazing Javascript library to manage Date objects and extremely light weight at 40kb.
Good Luck.