Automate Text Formatting in Google Docs with Google Apps Script

function boldParagraphStarters() {
  const doc = DocumentApp.getActiveDocument();
  const body = doc.getBody();
  const paragraphs = body.getParagraphs();

  const targetWords = ['Objective:', 'Explanation:'];
  const pattern = new RegExp(`^(${targetWords.join('|')})\s*(.*)`, 'i');

  paragraphs.forEach(paragraph => {
    let text = paragraph.getText();
    const match = text.match(pattern);
    if (match) {
      const starterWord = match[1].split(':')[0];
      const remainingText = text.substring(starterWord.length + 1).trim();
      paragraph.clear();
      paragraph.appendText(starterWord).setBold(true);
      paragraph.appendText(`: ${remainingText}`);
    }
  });
}