JSFiddle - React, Tailwind, and code Playground

HTML

<form id="booking" action="">
            <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(dateTime.value)"/>
            <input type="reset" value="Reset">

        </form>

JavaScript

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



var today = new Date().toISOString().split('T')[0];

document.getElementById("dateTime").setAttribute('min', today);


function getData (dateString) {
  console.log(dateString);
  var date = convertDateToUTC(new Date(dateString));
  var now = new Date();
  console.log(date, now, date > now);
  if (isNaN(date.getTime()) || date <= now) {
    console.log('Choose date in the future');
  }
}

function convertDateToUTC(date) { 
    return new Date(date.getUTCFullYear(), date.getUTCMonth(), date.getUTCDate(), date.getUTCHours(), date.getUTCMinutes(), date.getUTCSeconds()); 
}