JavaScript validate date and return last available date of calendar

Question

I want to validate my date if date not exits in calendar then return me last available date of calendar,

Example 01

Input Date    : 31         


        

Answer 1

function isValidDate(year, month, day) {
    var d = new Date(year, month, day);
    if (d.getFullYear() == year && d.getMonth() == month && d.getDate() == day) {
        return d;
    }
    else
        rturn new Date(year, month, 0);;
}