JavaScript date verification: the input date is greater than or equal to the current date_javascript skills

<script>
  $(function () {
    var d = new Date();

    var strDate = getDateStr(d);
    $("#beginTime").val(strDate);
    $("#endTime").val(strDate);
    //$("#beginTime").val("2015-10-10");

    $("#beginTime").change(function () {
    var d2 = new Date($("#beginTime").val());
    if (d2 < d) {
      alert("填写的动工日期必须大于当前日期.");
      $("#beginTime").val(strDate);
    }
    });
    $("#endTime").change(function () {
    var d2 = new Date($("#beginTime").val());
    var d3 = new Date($("#endTime").val());
    if (d3< d2) {
      alert("填写的完工日期不能小于动工日期.");
      $("#endTime").val(getDateStr(d2));
    }
    });
  });

  function getDateStr(date) {
    var month = date.getMonth() + 1;
    var strDate = date.getFullYear() + '-' + month + '-' + date.getDate();
    return strDate;
  }
</script>