Javascript验证表单返回false不能在IOS的Safari浏览器上运行

Question

我已写好检查日期的条件，如果交货时间少于4小时，则显示错误消息，不允许采取进一步措施。在Android手机和网站上，它运行良好。

在Iphone Safari浏览器中，它不显示我的消息，并且不返回false，并继续执行下一步操作。我的代码有什么问题

function validate_form() {
  var mytext = "";
  document.getElementById("mytext").innerHTML = "";

  if ($("#pickup_time").val().trim() !== "") {
    var inputDate = new Date($("#pickup_time").val().trim());
    var todaysDate = new Date();

    if (inputDate.setHours(0, 0, 0, 0) == todaysDate.setHours(0, 0, 0, 0)) {
      var pickup_time = $("#pickup_time").val().trim();
      var pickup_min = pickup_time.substr(pickup_time.length - 2);
      pickup_time = pickup_time.substr(pickup_time.length - 5);
      pickup_time = pickup_time.substr(0, 2);
      var date = new Date();
      var hours = date.getHours() < 10 ? "0" + date.getHours() : date.getHours();
      var minutes = date.getMinutes() < 10 ? "0" + date.getMinutes() : date.getMinutes();
      hours = hours + 4;

      if (pickup_time === hours) {
        if (pickup_min >= minutes) {
          return true;
        } else {
          document.getElementById("mytext").innerHTML = "Minimum lead time required is 4Hrs to schedule a Car!";
          return false;
        }
      } else if (pickup_time < hours) {
        document.getElementById("mytext").innerHTML = "Minimum lead time required is 4Hrs to schedule a Car!";
        return false;
      }
    }
  }
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<form action="success.html" method="post" class="chafviews" id="booknow" onsubmit="return validate_form(event)">
  <div class="pickCont">
    <input type="text" class="textField pick_datepicker" value="" name="pickup_time" id="pickup_time" placeholder="Select start date" />
    <div class="fieldLable">Pickup Date and Time</div>
  </div>
  <div class="pickCont">
    <input type="text" class="textField drop_datepicker" value="" name="dropoff_time" id="dropoff_time" placeholder="Select end date" />
    <div class="fieldLable">Drop-off Date and Time</div>
  </div>
  <p id="mytext" style="color: red; margin-top: 50px; font-size: 13px;"></p>
  <input type="submit" class="selfBook" value="Proceed" />
</form>