Apps Script code that adds a horizontal line above each Heading 4

Apps Script Code

function addHorizontalLineAboveHeading4() {
  const DOCID = 'YOUR_DOCUMENT_ID_HERE'; // Replace with your Document ID
  const doc = DocumentApp.openById(DOCID);
  const body = doc.getBody();
  const paragraphs = body.getParagraphs();

  // Iterate through the paragraphs in reverse order
  for (let i = paragraphs.length - 1; i >= 0; i--) {
    const paragraph = paragraphs[i];

    // Check if the paragraph is a Heading 4
    if (paragraph.getHeading() === DocumentApp.ParagraphHeading.HEADING4) {
      // Insert a horizontal line above the Heading 4 element
      body.insertHorizontalRule(i);
      Logger.log(`Added horizontal line above Heading 4 at index: ${i}`);
    }
  }

  Logger.log("Processed all Heading 4 elements.");
}

---

How It Works

1. Target Heading 4:
   • The script identifies paragraphs styled as Heading 4 using paragraph.getHeading().
2. Iterate Backwards:
   • The loop iterates through the paragraphs in reverse order (for (let i = paragraphs.length - 1; i >= 0; i--)) to ensure that the indices remain consistent when inserting horizontal lines.
3. Insert Horizontal Line:
   • A horizontal line is added above the Heading 4 element using body.insertHorizontalRule(i).
4. Logging:
   • Logs are added for each update, making it easier to debug and verify the changes.

---

Example

Before:

This is a normal paragraph.
Heading 4: Section 1
Heading 4: Section 2
This is another paragraph.

After:

This is a normal paragraph.
---------------------
Heading 4: Section 1
---------------------
Heading 4: Section 2
This is another paragraph.

---

Steps to Use

1. Set Up Apps Script:
   • Open your Google Drive and navigate to Extensions > Apps Script.
   • Paste the code into the script editor.
2. Replace the Document ID:
   • Replace 'YOUR_DOCUMENT_ID_HERE' with the ID of your Google Doc. The ID is found in the URL between /d/ and /edit.
3. Run the Script:
   • Click the Run button in the Apps Script editor. Authorize the script if prompted.
4. Verify Changes:
   • Open your Google Doc and confirm that a horizontal line has been added above each Heading 4.

---

Why Start from the End?

Starting from the end ensures that inserting a horizontal line does not affect the indices of subsequent paragraphs. This is crucial for maintaining consistent behavior in iterative scripts.