Include tax in OSRS Wiki Prices margin and profit calculations

DoUrTaxes.user.js

// ==UserScript==
// @name        Do Ur Taxes
// @namespace   Violentmonkey Scripts
// @match       https://prices.runescape.wiki/osrs*
// @grant       GM_xmlhttpRequest
// @version     1.44
// @author      neck
// @description Include tax in OSRS Wiki Prices margin and profit calculations
// @run-at      document-start
// ==/UserScript==
// this script will only work in firefox
// https://developer.mozilla.org/en-US/docs/Web/API/Element/beforescriptexecute_event
// script interception code
// https://stackoverflow.com/a/43678483

function editScript(text) {
  // https://oldschool.runescape.wiki/w/Grand_Exchange#Exempt_from_tax
  // Watering can (0) has no listing on prices.runescape.wiki
  // [Old school bond, Chisel, Gardening trowel, Glassblowing pipe, Hammer, Needle, Pestle and mortar, Rake, Saw, Secateurs, Seed dibber, Shears, Spade]
  const taxExempt = "[13190,1755,5325,1785,2347,1733,233,5341,8794,5329,5343,1735,952]";
  // regex (guh) to avoid relying on random minified function & variable names
  const marginFuncRe = /(([a-zA-Z]{2})=function\(([a-zA-Z]),([a-zA-Z]))(\){return (\3&&\4))(\?\3-\4:null})/;
  const roiRe = /(([a-zA-Z])=(\(([a-zA-Z])=([a-zA-Z]).high,([a-zA-Z])=\5.low,)(\(\4-\6\))(\/\6\*100\)))/;
  const marginFuncName = text.match(marginFuncRe)[2];
  const idToMarginRe = new RegExp("(" + marginFuncName + "\\(([a-zA-Z])\\.high,\\2\\.low)\\)", "g");
  const highAlchMarginRe = new RegExp(marginFuncName + "\\((([a-zA-Z])\\.highalch),(\\2\\.high\\+[a-zA-Z].high)\\)");
  text = text.replace(marginFuncRe, `$1,i$5&&!${taxExempt}.includes(i)?$3-$4-(Math.min(Math.floor($3*0.01),5000000)):$6&&${taxExempt}.includes(i)$7`);
  text = text.replace(roiRe, `$2=!${taxExempt}.includes($5.id)?$3($7-(Math.min(Math.floor($4*0.01),5000000)))$8:$1`);
  text = text.replace(idToMarginRe, "$1,$2.id)");
  text = text.replace(highAlchMarginRe, "$1-($3)");
  return text;
}

function addScript(text) {
  const newScript = document.createElement("script");
  const head = document.getElementsByTagName("head")[0];
  newScript.type = "text/javascript";
  newScript.textContent = editScript(text);
  head.appendChild(newScript);
}

window.addEventListener("beforescriptexecute", function(e) {
  const src = e.target.src;
  if (src && src.startsWith("https://prices.runescape.wiki/osrs/static/js/main")) {
    e.preventDefault();
    e.stopPropagation();
    GM_xmlhttpRequest({
      method: "GET",
      url: src,
      onload: function(response) {
        addScript(response.responseText);
      }
    });
  }
});