How to check if jQuery properties have been set in JavaScript and PHP?

Question

Before I being, let me clarify I am a newbie to jQuery and JavaScript. I'm sorry if the answer is obvious Okay, I am trying to create a page where the user can select dates and times, and want to use JavaScript and PHP to make sure the user is not returning a blank field (like no date or time set and clicks submit). I am using jQuery's datepicker and a timepicker from Jon Thornton. I successfully created the fields to display that, but I don't know the proper way to call it in JavaScript and check. Here is my code as of now:

    <script src="https://code.jquery.com/jquery-1.12.4.js"></script>
<script src="https://code.jquery.com/ui/1.12.1/jquery-ui.js"></script>
<link rel="stylesheet" href="//code.jquery.com/ui/1.12.1/themes/base/jquery-ui.css">
<script type='text/javascript' src='../jQuery/jonthornton-jquery-timepicker-dbdea8e/jquery.timepicker.js'></script>
<link rel='stylesheet' href='../jQuery/jonthornton-jquery-timepicker-dbdea8e/jquery.timepicker.css'>
<script>
  $( function() {
    $( "#datepicker" ).datepicker({maxDate: "+2M", dateFormat: 'yy-mm-dd'});
  } );
    $(function(){
   $('.scrollDefaultExample').timepicker({ 'scrollDefault': 'now' }); 
});
</script>

<script>
function validateForm() {
    var date = document.forms["Time_Slot"]["datePick"].value;
    var date2 = document.getElementById("datepicker");
    var main_timeSlot = document.forms["Time_Slot"]["timeSlot"].value;
    var add1 = document.forms["Time_Slot"]["additional_1"].value;
    var add2 = document.forms["Time_Slot"]["additional_2"].value;
    var add3 = document.forms["Time_Slot"]["additional_3"].value;
    var add4 = document.forms["Time_Slot"]["additional_4"].value;
    var add5 = document.forms["Time_Slot"]["additional_5"].value;
    var add1Box = document.forms["Time_Slot"]["additional_1_box"].value;
    var add2Box = document.forms["Time_Slot"]["additional_2_box"].value;
    var add3Box = document.forms["Time_Slot"]["additional_3_box"].value;
    var add4Box = document.forms["Time_Slot"]["additional_4_box"].value;
    var add5Box = document.forms["Time_Slot"]["additional_5_box"].value;
    alert("yolo");
    console.log(date);
    if (date2 == null || date == "" || date == " ") {
        alert("A date must be chosen!");
        return false;
    }
    else if (lname == null || lname == "" || lname == " ") {
        alert("The last name field should be complete!");
        return false;
    }
    else if (email == null || email == "" || email == " ") {
        alert("The email field should be complete!");
        return false;
    }
    else if (password == null || password == "" || password = " ") {
        alert("A valid password must be entered! Note: it cannot contain just a space.");
        return false;
    }
}
</script>

<form name="Time_Slot" method="POST">
    <fieldset>
        <p>Date: <input type="text" id="datepicker" name="datePick"></p>
        <p>Time: <input type="text" class="scrollDefaultExample" name="timeSlot"></p>
        <br>
        <label><input type="checkbox" name="additional_1" value="extra_1"> Additional Time Slot: <input type="text" class="scrollDefaultExample" name="additional_1_box"></label> <br><br>

        <label><input type="checkbox" name="additional_2" value="extra_2"> Additional Time Slot: <input type="text" class="scrollDefaultExample" name="additional_2_box"></label> <br><br>

        <label><input type="checkbox" name="additional_3" value="extra_3"> Additional Time Slot: <input type="text" class="scrollDefaultExample" name="additional_3_box"></label> <br><br>

        <label><input type="checkbox" name="additional_4" value="extra_4"> Additional Time Slot: <input type="text" class="scrollDefaultExample" name="additional_4_box"></label> <br><br>

        <label><input type="checkbox" name="additional_5" value="extra_5"> Additional Time Slot: <input type="text" class="scrollDefaultExample" name="additional_5_box"></label> <br><br>

        <p><input type="submit" name="submit" value="Create Available Appointments"  onclick="return validateForm()"></p>
    </fieldset>
</form>

When I click on the button to submit, I am not being warned that the date is not set. It would be grateful of you if you can show me a way. Thank you in advance!

Answer 1

To take this a little further, why not implement jQueryValidate? (https://jqueryvalidation.org/)

It's a little overkill for what you need here As you're implementing other validation functions it's worth adding, but simply by adding "required" in the input element, it will do what you ask - and when you start developing more you'll really like the additional features available.

<!-- include the validation script, from CDN or download -->
<script src='    http://ajax.aspnetcdn.com/ajax/jquery.validate/1.15.0/jquery.validate.min.js'></script>

<!-- On document ready, find hte form and add the validation function -->
<script>
   $.ready(function() {
         $('form[name="Time_Slot"]').validate();
   });
</script> 

<!-- In the input, add "required" -->
<input type="text" id="datepicker" name="datePick" required>

The code is written untested, but should be enough to get you started.