Diatonic (10H) to Tremolo (20H) Harmonica Convertor [Suzuki Winner Harmonica]

tremolo_converter.user.js

// ==UserScript==
// @name         Tremolo converter
// @namespace    https://gist.github.com/skaveesh/ab93df4414732e69ad1cb0204dcb20b1
// @version      0.1
// @description  try to take over the world!
// @author       Samintha Kaveesh
// @match        https://www.harptabs.com/*
// @icon         https://www.google.com/s2/favicons?sz=64&domain=harptabs.com
// @grant        none
// @run-at       document-end
// ==/UserScript==

(function() {
    'use strict';

    const regex = /-?.[0-9][\*\']|\/[0-9]/gi;
    const numbers = /-?[0-9]\d*/gi;

    var tabs = getElementByXpath("//html/body/center/table/tbody/tr[3]/td[1]/table[1]/tbody/tr[1]/td[2]/center/table[3]/tbody/tr/td[2]");

    console.log(tabs.innerText);

    tabs.innerHTML = tabs.innerHTML
        .replaceAll(regex,"<span style='color: red'>X</span>")
        .replace(numbers, function replace(match) {
        return '<emx>' + match + '</emx>';
    })
        .replaceAll("<emx>2</emx>", "3")
        .replaceAll("<emx>1</emx>", "1")
        .replaceAll("<emx>3</emx>", "5")
        .replaceAll("<emx>4</emx>", "7")
        .replaceAll("<emx>5</emx>", "9")
        .replaceAll("<emx>6</emx>", "11")
        .replaceAll("<emx>7</emx>", "13")
        .replaceAll("<emx>8</emx>", "15")
        .replaceAll("<emx>9</emx>", "17")
        .replaceAll("<emx>10</emx>", "19")
        .replaceAll("<emx>-1</emx>", "-2")
        .replaceAll("<emx>-2</emx>", "-4")
        .replaceAll("<emx>-3</emx>", "-6")
        .replaceAll("<emx>-4</emx>", "-8")
        .replaceAll("<emx>-5</emx>", "-10")
        .replaceAll("<emx>-6</emx>", "-12")
        .replaceAll("<emx>-7</emx>", "-14")
        .replaceAll("<emx>-8</emx>", "-16")
        .replaceAll("<emx>-9</emx>", "-18")
        .replaceAll("<emx>-10</emx>", "-20");


    console.log(tabs.innerText);
})();

function getElementByXpath(path) {
  return document.evaluate(path, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;
}

This script can be installed with Tampermonkey to use in https://www.harptabs.com/ with Diatonic harp tabs with the key of C.