get Year only from input field type="date" in lightning component controller

Thanks Anjali...for the reference link.

but i need to get only year value of input date type field so that i use it for comparison purpose and got that solution..

from input field i taken value using aura:id and did following process for deducting it from current year.

var date=component.find('DOB').get('v.value');
var splite= date.split('-');
var num=parseInt(splite[0]);
var today = new Date();
var currentYear = today.getFullYear(); //system generated todays date(year)...
var ageDifference=currentYear -num;