Google Docs Encode

function onOpen() {
  var ui = DocumentApp.getUi();
  // Or DocumentApp or FormApp.
  ui.createMenu('Dialog')
      .addItem('Open', 'openDialog')
      .addToUi();
  ui.createMenu('TentoezTools')
      .addSubMenu(ui.createMenu('Crypt')
           .addItem('Encode', 'encode')
           .addItem('Decode', 'decode'))
      .addToUi();
}

function encode() {
  var body = DocumentApp.getActiveDocument().getBody();
  var ui = DocumentApp.getUi();
  var result = ui.prompt(
      'Enter your encoding key',
      'Enter your 2 digit encoding key',
      ui.ButtonSet.OK_CANCEL);

  // Process the user's response.
  var button = result.getSelectedButton();
  var key = result.getResponseText();
  if (button == ui.Button.OK) {
    for (var i = 1; i <= key; i++){
      var text = body.editAsText()
      text.replaceText("b","9442")
      text.replaceText("c","b")
      text.replaceText("d","c")
      text.replaceText("e","d")
      text.replaceText("f","e")
      text.replaceText("g","f")
      text.replaceText("h","g")
      text.replaceText("i","h")
      text.replaceText("j","i")
      text.replaceText("k","j")
      text.replaceText("l","k")
      text.replaceText("m","l")
      text.replaceText("n","m")
      text.replaceText("o","n")
      text.replaceText("p","o")
      text.replaceText("q","p")
      text.replaceText("r","q")
      text.replaceText("s","r")
      text.replaceText("t","s")
      text.replaceText("u","t")
      text.replaceText("v","u")
      text.replaceText("w","v")
      text.replaceText("x","w")
      text.replaceText("y","x")
      text.replaceText("z","y")
      text.replaceText("a","z")
      text.replaceText("9442","a")}
  }
}

function decode() {
  var body = DocumentApp.getActiveDocument().getBody();
  var ui = DocumentApp.getUi();
  var result = ui.prompt(
      'Enter your encoding key',
      'Enter your 2 digit encoding key',
      ui.ButtonSet.OK_CANCEL);

  // Process the user's response.
  var button = result.getSelectedButton();
  var key = result.getResponseText();
  if (button == ui.Button.OK) {
    for (var i = 1; i <= key; i++){
      var text = body.editAsText()
      text.replaceText("z","9442")
      text.replaceText("y","z")
      text.replaceText("x","y")
      text.replaceText("w","x")
      text.replaceText("v","w")
      text.replaceText("u","v")
      text.replaceText("t","u")
      text.replaceText("s","t")
      text.replaceText("r","s")
      text.replaceText("q","r")
      text.replaceText("p","q")
      text.replaceText("o","p")
      text.replaceText("n","o")
      text.replaceText("m","n")
      text.replaceText("l","m")
      text.replaceText("k","l")
      text.replaceText("j","k")
      text.replaceText("i","j")
      text.replaceText("h","i")
      text.replaceText("g","h")
      text.replaceText("f","g")
      text.replaceText("e","f")
      text.replaceText("d","e")
      text.replaceText("c","d")
      text.replaceText("b","c")
      text.replaceText("a","b")
      text.replaceText("9442","a")}
  }
}

function openDialog() {
  var html = HtmlService.createHtmlOutputFromFile('Index');
  DocumentApp.getUi() // Or DocumentApp or FormApp.
      .showModalDialog(html, 'Dialog title');
}