HeadingLevelNumbering.gs

// Heading Level Numbering for Google Docs
// Created by Sohail Ahmed 
// Created On October 3, 2023

// This series of functions will install an 'Auto Numbering' menu with a couple of options in it.
// The most important is 'Update Heading Numbers', which will generate/update outline numbering.

function onOpen() {
  updateMenu();
}

function updateMenu() {
  var ui = DocumentApp.getUi();
  var numberLevel1 = isNumberLevel1();
  var menuItemText = numberLevel1 ? 'Hide Level 1 Numbers' : 'Show Level 1 Numbers';
  ui.createMenu('Auto Numbering')
    .addItem('Update Heading Numbers', 'initiateHeadingUpdate')
    .addItem(menuItemText, 'toggleNumberLevel1')
    .addToUi();
}

function isNumberLevel1() {
  return PropertiesService.getScriptProperties().getProperty('numberLevel1') === 'true';
}

function toggleNumberLevel1() {
  var numberLevel1 = isNumberLevel1();
  PropertiesService.getScriptProperties().setProperty('numberLevel1', !numberLevel1);
  updateMenu();
}

function initiateHeadingUpdate() {
  var doc = DocumentApp.getActiveDocument();
  var body = doc.getBody();

  var bookmark;
  
  try {
    // Create a temporary bookmark at the current cursor position.
    var selection = doc.getSelection();
    if (selection) {
      var rangeElements = selection.getRangeElements();
      if (rangeElements.length > 0) {
        var position = rangeElements[0].getStartOffset();
        var element = rangeElements[0].getElement();
        
        if (doc.createBookmark) {
          bookmark = doc.createBookmark(element, position);
        } else {
          console.warn('doc.createBookmark method not available.');
        }
      }
    }
  } catch (e) {
    console.error("Bookmark creation failed: ", e);
  }
  
  // Update the headings
  updateHeadings();

  // Open the sidebar, which forces Google Docs to navigate to the bookmark's position.
  DocumentApp.getUi().showSidebar(HtmlService.createHtmlOutput("<script>window.onload = function() { google.script.run.closeSidebar(); }</script>"));
  
  try {
    // Remove the bookmark.
    if (bookmark) {
      bookmark.remove();
    }
  } catch (e) {
    console.error("Bookmark removal failed: ", e);
  }
}

function closeSidebar() {
  DocumentApp.getUi().closeDialog();
}

function updateHeadings() {
  var doc = DocumentApp.getActiveDocument();
  var body = doc.getBody();
  var paragraphs = body.getParagraphs();
  var numberLevel1 = isNumberLevel1();
  
  var currentLevelNumbers = [0, 0, 0, 0, 0, 0];  // supports up to 6 levels of headings
  
  for (var i = 0; i < paragraphs.length; i++) {
    var paragraph = paragraphs[i];
    var heading = paragraph.getHeading();
    
    // Skip empty paragraphs
    if (!paragraph.getText().trim()) {
      continue;
    }
    
    // If it's a heading (not NORMAL or TITLE or SUBTITLE)
    if (heading !== DocumentApp.ParagraphHeading.NORMAL &&
        heading !== DocumentApp.ParagraphHeading.TITLE &&
        heading !== DocumentApp.ParagraphHeading.SUBTITLE) {
      
      var level;
      switch(heading) {
        case DocumentApp.ParagraphHeading.HEADING1:
          level = 1;
          break;
        case DocumentApp.ParagraphHeading.HEADING2:
          level = 2;
          break;
        case DocumentApp.ParagraphHeading.HEADING3:
          level = 3;
          break;
        case DocumentApp.ParagraphHeading.HEADING4:
          level = 4;
          break;
        case DocumentApp.ParagraphHeading.HEADING5:
          level = 5;
          break;
        default:
          level = 0;
      }
      
      // Increment the current level number and reset all sub-levels to 0
      currentLevelNumbers[level - 1]++;
      for (var j = level; j < currentLevelNumbers.length; j++) {
        currentLevelNumbers[j] = 0;
      }
      
      var numbering = currentLevelNumbers.slice(0, level).join('.');
      if (level !== 1 || (level === 1 && numberLevel1)) {
        // Set the updated text for all levels when numberLevel1 is true,
        // or for levels other than 1 when numberLevel1 is false
        var text = paragraph.getText();
        text = text.replace(/^\d+(\.\d+)*(\s*\.\s*)?\s*/, '');
        paragraph.setText(numbering + ' ' + text.trim());
      } else if (level === 1 && !numberLevel1) {
        // Remove numbering from Level 1 headings when numberLevel1 is false
        var text = paragraph.getText();
        text = text.replace(/^\d+(\.\d+)*(\s*\.\s*)?\s*/, '');
        paragraph.setText(text.trim());
      }
    }
  }
}