GAS google docs auto sequencer

sequencer.js

var _ = Underscore.load();

var HeadingCounter,
  __indexOf = [].indexOf || function(item) { for (var i = 0, l = this.length; i < l; i++) { if (i in this && this[i] === item) return i; } return -1; };

HeadingCounter = (function() {

  HeadingCounter.name = 'HeadingCounter';
  HeadingCounter.HEADINGS = [DocumentApp.ParagraphHeading.HEADING1.toString(), 
                             DocumentApp.ParagraphHeading.HEADING2.toString(), 
                             DocumentApp.ParagraphHeading.HEADING3.toString(), 
                             DocumentApp.ParagraphHeading.HEADING4.toString(), 
                             DocumentApp.ParagraphHeading.HEADING5.toString(), 
                             DocumentApp.ParagraphHeading.HEADING6.toString()];


  function HeadingCounter() {
    this.counter = {};
    this.reset();
  }

  HeadingCounter.prototype.reset = function(level) {
    var h, i, _i, _len, _level, _ref;
    if (level == null) level = DocumentApp.ParagraphHeading.HEADING1;
    _level = level.toString();
    i = HeadingCounter.HEADINGS.indexOf(_level);
    _ref = HeadingCounter.HEADINGS.slice(i);
    for (_i = 0, _len = _ref.length; _i < _len; _i++) {
      h = _ref[_i];
      this.counter[h] = 0;
    }
  };

  HeadingCounter.prototype.increment = function(level) {
    var _level;
    _level = level.toString();
    if (this.counter.hasOwnProperty(_level)) {
      this.counter[_level]++;
      var next_level = HeadingCounter.HEADINGS[HeadingCounter.HEADINGS.indexOf(_level)+1];
      this.reset(next_level);
    }
    return this.counter[_level];
  };

  HeadingCounter.prototype.sequence = function(level) {
    var i, _level;
    _level = level.toString();
    if (__indexOf.call(HeadingCounter.HEADINGS, _level) >= 0) {
      i = HeadingCounter.HEADINGS.indexOf(_level);
      var _this = this;
      return _.map(HeadingCounter.HEADINGS.slice(0, i + 1 || 9e9), function(num) {
        return _this.counter[num];
      });
    } else {
      return;
    }
  };

  return HeadingCounter;

})();

function onOpen() {
  // Add a menu with some items, some separators, and a sub-menu.
  DocumentApp.getUi().createMenu('Sequencer')
      .addItem('実行', 'execute')
      .addToUi();
}

function execute() {
  var body = DocumentApp.getActiveDocument().getBody();
  var paragraphs = body.getParagraphs();
  
  var counter = new HeadingCounter();
  for each (p in paragraphs) {
    var h = p.getHeading();
    counter.increment(h);
    var level = counter.sequence(h)
    if (level) {
      p.setText(replace_heading(level, p.getText()));
    }
  }
}

function replace_heading(level, text) {
  var stripped;
  stripped = text.replace(/^(\d\+.){1,}/i, '').replace(/(^\s+)|(\s+$)/g, "");
  level.push(' ');
  return level.join('.') + stripped;
}