Raffleminer.com throttle script

Automatically throttle raffleminer.com's CPU mining speed
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Wrap lines
// ==UserScript==
// @name         Raffleminer.com throttle script
// @namespace    jasonheecs
// @version      1.2
// @description  Automatically throttle raffleminer.com's CPU mining speed
// @author       Jason Hee
// @license      MIT
// @include https://www.raffleminer.com/
// @grant   GM_getValue
// @grant   GM_setValue
// @grant   GM_registerMenuCommand
// ==/UserScript==

(function () {
  'use strict';

  /**
     * Set a tampermonkey script's variable to be user definable
     * @param  {string} varName
     * @param  {*} defaultVal
     * @param  {Function} parseFunc
     * @return {Function}
     */
  function makeUserModifiable (varName, defaultVal, parseFunc) {
    if (typeof parseFunc !== 'function') {
      parseFunc = function (a) { return a; };
    }

    var currentVal = GM_getValue(varName, defaultVal);
    GM_registerMenuCommand('Set variable ' + varName, function () {
      var val = window.prompt('Value for ' + varName, currentVal);
      GM_setValue(varName, val);
      window.location.reload();
    });

    return parseFunc(currentVal);
  }

  /**
     * Observe mutation changes for a dom element
     * @param  {Node}   domEl
     * @param  {Function} callback
     */
  function observeNode (domEl, callback) {
    var MutationObserver = window.MutationObserver || window.WebKitMutationObserver;

    var observer = new MutationObserver(function (mutationsList) {
      for (var mutation of mutationsList) {
        callback(mutation, domEl);
      }
    });

    observer.observe(domEl, { characterData: false, attributes: false, childList: true, subtree: false });
  }

  var $ = function (selector) {
    return document.getElementById(selector) || document.querySelector(selector);
  };

  var nanoWalletAddress = makeUserModifiable('nanoWalletAddress', '');
  var maxMiningSpeed = makeUserModifiable('maxMiningSpeed', '10', parseInt);
  var toggleMiningEl = $('toggle-mining');
  var decreaseMiningSpeedEl = $('throttle-dec');

  if (!nanoWalletAddress.length) {
    return;
  }

  $('nano_account').value = nanoWalletAddress;

  toggleMiningEl.addEventListener('click', function () {
    observeNode($('mine-status'), function (mutation) {
      if (mutation.addedNodes.length && mutation.addedNodes[0].data === 'You are generating hashes, good luck in the raffle!') {
        while (parseInt($('mine-throttle').textContent) > maxMiningSpeed) {
          decreaseMiningSpeedEl.click();
        }
      }
    });
  });

  toggleMiningEl.click();
})();