Adding capabilities of registered users of eCalc to everyone

eCalcHack

// ==UserScript==
// @name        eCalcHack
// @namespace   froller
// @description Adding capabilities of registered users of eCalc to everyone
// @include     http://www.ecalc.ch/motorcalc.php*
// @include     http://www.ecalc.ch/xcoptercalc.php*
// @include     http://www.ecalc.ch/fancalc.php*
// @include     http://www.ecalc.ch/helicalc.php*
// @version     1
// @grant       none
// ==/UserScript==

var hackables = [];

function disableObjects(objects, disable) {
  for (var idx in objects) {
    if (disable) {
      objects[idx].setAttribute("disabled", "");
    } else {
      objects[idx].removeAttribute("disabled");
    }
  }
}

function hackInputs() {
  disableObjects(hackables, false);
}

function unHackInputs() {
  disableObjects(hackables, true);
}

function mkHackBtn() {
  var btn = document.createElement("input");
  btn.setAttribute("type", "button");
  btn.setAttribute("value", "Hack!");
  btn.addEventListener("click", hackInputs, false);
  return btn;
}

function addButtons() {
  var td = document.getElementsByClassName("inputProp")[14];
  td.appendChild(document.createElement("br"));
  td.appendChild(mkHackBtn());
}

function getHackables() {
  var inputs = document.getElementsByTagName("input");
  var disabledInputs = [];
  for (var idx in inputs) {
    if (inputs[idx].id && inputs[idx].hasAttribute("disabled")) {
      disabledInputs.push(inputs[idx]);
    }
  }
  disabledInputs.push(document.getElementById("inMLimitType"));
  return disabledInputs;
}

function hackedCalculateHandler() {
  unHackInputs();
  calculate();
}

function hackCalculate() {
  var btn = document.getElementsByName("btnCalculate")[0];
  btn.removeAttribute("onclick");
  btn.removeEventListener("click", calculate);
  btn.addEventListener("click", hackedCalculateHandler, false);
}

hackables = getHackables();
addButtons();
hackInputs();
hackCalculate();