Violentmonkey script to add m² price to plywood pricelist

vineerimaailm.user.js

// ==UserScript==
// @name        Show m2 price - vineerimaailm.ee
// @namespace   Violentmonkey Scripts
// @match       https://vineerimaailm.ee/outlet
// @grant       none
// @version     1.0
// @author      Cougar
// @description 8/18/2023, 4:34:14 PM
// ==/UserScript==

window.updateTable = function() {
  if (document.getElementById("m2price")) {
    return;
  }
  var table = $("#resHTML").find("table");
  $('<col style="width: 160px;">').insertAfter($(table.find("colgroup > col:eq(7)")));
  $('<th id="m2price"><strong>HIND (EUR/m²)</strong></th>').insertAfter($(table.find("thead > tr > th:eq(7)")));
  $(table).find("tbody > tr").each(function(i) {
    var processElement = $(this);
    var t = $(this).find(".thick").html();
    var l = $(this).find(".length").html();
    var w = $(this).find(".width").html();
    var p = $(this).find(".price").html().trim().slice(0,-1).replace(',', '.');
    var m2 = (p / (l * w / 1000000));
    var m2t = (m2 / t) * 6;
    $('<td class="m2price">' + m2.toFixed(2).replace('.', ',') + '€ (' + m2t.toFixed(2).replace('.', ',') + ')</td>').insertAfter($(this).find(".price"));
  })
}

$(document).ready(function() {
  $('<h1><button type="button" class="btn" onclick="updateTable()">Näita m² hind</button></h1>').insertBefore("#resHTML");
  updateTable();
});