JSFiddle - React, Tailwind, and code Playground

HTML

<select id="ophalenUur" class="timePicker selectOption">
<option value="-">Kies Tijd</option>
  <option value="8">08.00</option>
  <option value="8.5">08.30</option>
  <option value="9">09.00</option>
  <option value="9.5">09.30</option>
  <option value="10">10.00</option>
  <option value="10.5">10.30</option>
  <option value="11">11.00</option>
  <option value="11.5">11.30</option>
  <option value="12">12.00</option>
  <option value="12.5">12.30</option>
  <option value="13">13.00</option>
  <option value="13.5">13.30</option>
  <option value="14">14.00</option>
  <option value="14.5">14.30</option>
  <option value="15.">15.00</option>
  <option value="15.5">15.30</option>
  <option value="16">16.00</option>
  <option value="16.5">16.30</option>
  <option value="17">17.00</option>
  <option value="17.5">17.30</option>
  <option value="18">18.00</option>
  <option value="18.5">18.30</option>
  <option value="19">19.00</option>
  <option value="19.5">19.30</option>
  <option value="20">20.00</option>
</select> 

<select id="inleverenUur" class="timePicker selectOption">
   <option class="defaultTime" value="-">Kies Tijd</option>
  <option value="8">08.00</option>
  <option value="8.5">08.30</option>
  <option value="9">09.00</option>
  <option value="9.5">09.30</option>
  <option value="10">10.00</option>
  <option value="10.5">10.30</option>
  <option value="11">11.00</option>
  <option value="11.5">11.30</option>
  <option value="12">12.00</option>
  <option value="12.5">12.30</option>
  <option value="13">13.00</option>
  <option value="13.5">13.30</option>
  <option value="14">14.00</option>
  <option value="14.5">14.30</option>
  <option value="15.">15.00</option>
  <option value="15.5">15.30</option>
  <option value="16">16.00</option>
  <option value="16.5">16.30</option>
  <option value="17">17.00</option>
  <option value="17.5">17.30</option>
  <option value="18">18.00</option>
  <option value="18.5">18.30</option>
  <option value="19">19.00</option>
 ...

JavaScript

var pickUp = 0;
var returnTime =0; 
var totalExtra = 0;

$('#ophalenUur').change(function() {
pickUp = $('#ophalenUur option:selected').val();
    $('.pickUp').text("PickUp: " + pickUp);
});

$('#inleverenUur').change(function() {
returnTime = $('#inleverenUur option:selected').val();
    $('.returntime').text("return: " + returnTime);
 if(parseFloat(returnTime) > parseFloat(pickUp)){
        alert("yea");
    }else{
        alert("no");           
    }
});