To add the number of days, use the Date() function to display the current date and then add two days
Example
Live Demo
<!DOCTYPE html>
<html>
<body>
<script>
var date, incDate;
date = new Date();
document.write(date);
var incDate = new Date(new Date().getTime()+(2*24*60*60*1000));
document.write("<br>"+incDate);
</script>
</body>
</html>