JSFiddle - React, Tailwind, and code Playground

HTML

<h4> Kjötálegg </h4>
    <input type="checkbox" name="meat[]" value="1">Pepperoni  <br>
    <input type="checkbox" name="meat[]" value="2">Skinka  <br>
    <input type="checkbox" name="meat[]" value="3">Nautahakk  <br>
    <input type="checkbox" name="meat[]" value="4">Beikon  <br> 
    <input type="checkbox" name="meat[]" value="5">Auka Pepperoni  <br>
    <input type="checkbox" name="meat[]" value="6">Kjúklingur  <br>

<div class="col-lg-2">
    <h4> Ostar </h4>
    <input type="checkbox" name="cheese[]" value="7">Gráðostur  <br>
    <input type="checkbox" name="cheese[]" value="8">Cheddarostur  <br>
    <input type="checkbox" name="cheese[]" value="9">Extra Ostur  <br>
    <input type="checkbox" name="cheese[]" value="10">Lítill Ostur  <br> 
    <input type="checkbox" name="cheese[]" value="11">Enginn Ostur  <br>
    <input type="checkbox" name="cheese[]" value="12">Rjómaostur  <br> 
    <input type="checkbox" name="cheese[]" value="13">Piparostur  <br>


    <input type="checkbox" name="greens[]" value="14">Græn Papripa<br>
    <input type="checkbox" name="greens[]" value="15">Laukur<br>
    <input type="checkbox" name="greens[]" value="16">Tómatsneiðar<br>
    <input type="checkbox" name="greens[]" value="17">Sveppir<br> 
    <input type="checkbox" name="greens[]" value="18">Ananas<br>
    <input type="checkbox" name="greens[]" value="19">Jalapenos<br> 
    <input type="checkbox" name="greens[]" value="20">Svartar Ólífur<br>
    <input type="checkbox" name="greens[]" value="21">Hvítlaukur<br>
    <input type="checkbox" name="greens[]" value="22">Rauðlaukur<br>
    <input type="checkbox" name="greens[]" value="23">Spínat<br>

    <input type="submit"/>

JavaScript

$(':input').click(function(event) {
    var count = 0;
    $(':input').each(function () {
        if (this.checked)
        {
            count++;   
        }
    });
    if (count > 2)
    {
        event.preventDefault();
        alert('You can only select 2!');
    }
});