Above solutions will work only if its a string. Input type date, gives you output in javascript date object in some cases like if you use angular or so. That's why some people are getting error like "TypeError: str.split is not a function". It's a date object, so you should use functions of Date object in javascript to manipulate it. Example here:
var date = $scope.dateObj ;
//dateObj is data bind to the ng-modal of input type dat.
console.log(date.getFullYear()); //this will give you full year eg : 1990
console.log(date.getDate()); //gives you the date from 1 to 31
console.log(date.getMonth() + 1); //getMonth will give month from 0 to 11
Check the following link for reference: