Google Apps Script that converts all Heading 3 styles to Heading 2 in a Google Docs document

Here’s a Google Apps Script that converts all Heading 3 (H3) styles to Heading 2 (H2) in a Google Docs document. It loops through all the paragraphs and updates the heading styles accordingly.

Steps to Use:

1. Open your Google Docs document.
2. Click on Extensions > Apps Script.
3. Delete any existing code and paste the script below.
4. Click the Run button to execute the script.

Apps Script:

function convertH3toH2() {
  var doc = DocumentApp.getActiveDocument();
  var body = doc.getBody();
  var paragraphs = body.getParagraphs();
  
  for (var i = 0; i < paragraphs.length; i++) {
    var para = paragraphs[i];
    if (para.getHeading() === DocumentApp.ParagraphHeading.HEADING3) {
      para.setHeading(DocumentApp.ParagraphHeading.HEADING2);
    }
  }
  
  Logger.log("Conversion complete: All H3 headings changed to H2.");
}

What This Script Does:

• Gets the active Google Docs document.
• Loops through all paragraphs.
• Checks if the paragraph is styled as Heading 3.
• Changes the style to Heading 2.