Validate the user entered date using JavaScript - buggy (UTC) - Gives invalid date for 01/01/1970

check-date.js

function checkDate(str)
{
    var matches = str.match(/(\d{1,2})[\/](\d{1,2})[\/](\d{4})/);
    if (!matches) return;
    var day = parseInt(matches[1],10);
    var month = parseInt(matches[2],10);
    var year = parseInt(matches[3],10);
    var date = new Date(year, month - 1, day);
    if (!date || !date.getTime()) return;
    if (date.getMonth() + 1 != month ||
        date.getFullYear() != year ||
        date.getDate() != day) {
            return;
        }
    return(date);
}