JAVASCRIPT

javascript check if date is less than today

function TDate() {
    var UserDate = document.getElementById("userdate").value;
    var ToDate = new Date();

    if (new Date(UserDate).getTime() <= ToDate.getTime()) {
          alert("The Date must be Bigger or Equal to today date");
          return false;
     }
    return true;
}

javascript date validation less than today

check this thread:
https://stackoverflow.com/questions/492994/compare-two-dates-with-javascript