如何检查jQuery属性是否已在JavaScript和PHP中设置？

Question

Before I being, let me clarify I am a newbie to jQuery and JavaScript. I'm sorry if the answer is obvious

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.