问JavaScript从表单中验证日期时间-本地

EN

/* Here is the JavaScript validation for the datetime-local. */

var dateTime = document.getElementById("dateTime").value;

if (dateTime == "" || dateTime == null) {
    booking.dateTime.focus();
    document.getElementById("dateMessage").innerHTML = "Please select a date AND time, thankyou.";
    return valid = false;
} else {
    document.getElementById("destinationMessage").innerHTML = "";
}

<div id="firstNameMessage" class="red"></div>

<span class="red">*</span>First Name:

<input type="text" name="firstName" id="firstName">

<br>

<div id="lastNameMessage" class="red"></div>

<span class="red">*</span>Last Name:

<input type="text" name="lastName" id="lastName">

<br>

<div id="numberMessage" class="red"></div>

<span class="red">*</span>Contact Number:

<input type="text" name="number" id="number">

<br>

<div id="unitMessage" class="red"></div>

Unit Number(optional):

<input type="text" name="unit" id="unit">

<br>

<div id="streetNumberMessage" class="red"></div>

<span class="red">*</span>Street Number:

<input type="text" name="streetNumber" id="streetNumber">

<br>

<div id="streetNameMessage" class="red"></div>

<span class="red">*</span>Street Name:

<input type="text" name="streetName" id="streetName">

<br>

<div id="pickupMessage" class="red"></div>

<span class="red">*</span>Suburb:

<input type="text" name="pickupSuburb" id="pickupSuburb">

<br>

<div id="destinationMessage" class="red"></div>

Destination Suburb<span class="red">*</span>:

<input type="text" name="destinationSuburb" id="destinationSuburb">

<br>

<div id="dateMessage" class="red"></div>

Pick-Up Date and Time<span class="red">*</span>:

<input type="datetime-local" name="dateTime" id="dateTime">

<br>

<br>

<input type="button" value="Submit"

    onclick="getData('bookingprocess.php','message', firstName.value, lastName.value, number.value, unit.value, streetNumber.value, streetName.value, pickupSuburb.value, destinationSuburb.value, dateTime.value)" />

<input type="reset" value="Reset">