google Apps script in google docs, how to change a single word to bold inside a paragraph?

I am trying to run an apps script function that should interpret text in a google document, and recognize markdown syntax, style it accordingly, and finally remove the markdown syntax characters.

I have been successfull converting # some headline to a heading 1, and ## sub header to a heading 2.

I would also like to generate bold elements. But It's proving challenging as bold text can occur in the middle of a sentence. And (I believe) that google documents split such a line into separate elements in the DOM.

The contents of my google document looks like this:

# Headline 1

## Secondary headline

Some **bold** text and some *italic text*
Some more text on a new line.

My apps script function:

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

  // Get the paragraphs in the document
  var paragraphs = body.getParagraphs();

  // Define the regular expression patterns to match Markdown styles
  var heading1Pattern = /^# (.*)$/;
  var heading2Pattern = /^## (.*)$/;
  var boldPattern = /\*\*(.*?)\*\*/g;

  // Process each paragraph for Markdown styles
  for (var i = 0; i < paragraphs.length; i++) {
    var paragraph = paragraphs[i];
    var text = paragraph.getText();

    // Process heading styles
    if (heading1Pattern.test(text)) {
      var modifiedText = text.replace(heading1Pattern, "$1");
      paragraph.setHeading(DocumentApp.ParagraphHeading.HEADING1);
      paragraph.setText(modifiedText);
    } else if (heading2Pattern.test(text)) {
      var modifiedText = text.replace(heading2Pattern, "$1");
      paragraph.setHeading(DocumentApp.ParagraphHeading.HEADING2);
      paragraph.setText(modifiedText);
    }

    // Process bold
    var boldMatches = text.matchAll(boldPattern);
    for (var match of boldMatches) {
      var originalText = match[0];
      var modifiedText = match[1];
      var text = paragraph.getText();
      var newText = text.replace(originalText, modifiedText); // remove astrix tags
      paragraph.setText(newText); // update paragraph
      paragraph.setBold(true); // This sets the entire line of text to bold, not just the word
    }
  }
}

In my function, where I update the text of the paragraph, I some how need to split it into several paragraphs I believe, and just set the desired one(s) to bold, but I can't figure out how to go about this - especially because there could be many bold words in one sentence separated with non-bold words. Any suggestions to an approach?

Solution

From your following reply,

But for now, the most important is headlines (1-6), and bold text. italic is not very important this moment

I believe your goal is as follows.

You want to change the style of # Header1, ## Header2,,, to header 1, header 2,,, respectively.
And also, you want to change the style of **bold** to the bold style.
You want to achieve this using Google Apps Script.

In this case, how about the following sample script?

Sample script:

function sample() {
  const headers = [...Array(6)].map((_, i) => ({ type: "header", search: `^#{${i + 1}} (.*)$`, c: i + 1, style: DocumentApp.ParagraphHeading[`HEADING${i + 1}`] })).reverse();
  const texts = [...Array(2)].map((_, i) => ({ type: "text", search: `\\*{${i + 1}}(.*?)\\*{${i + 1}}`, c: i + 1, style: i == 0 ? "setItalic" : "setBold" })).reverse();
  const searchPatterns = [...headers, ...texts];
  const search = (body, { type, search, c, style }) => {
    let s = body.findText(search);
    while (s) {
      const e = s.getElement();
      const start = s.getStartOffset();
      const end = s.getEndOffsetInclusive()
      if (type == "header") {
        const p = e.getParent();
        if (p.getType() == DocumentApp.ElementType.PARAGRAPH) {
          p.asParagraph().setHeading(style).editAsText().deleteText(0, c - 1);
        }
      } else if (type == "text") {
        e.asText()[style](start, end, true).deleteText(end - (c - 1), end).deleteText(start, start + (c - 1));
      }
      s = body.findText(search, s);
    }
  }
  const body = DocumentApp.getActiveDocument().getBody();
  searchPatterns.forEach(o => search(body, o));
}

In order to achieve your goal, I prepared a sample script by separating the header sections and the text.

Testing:

When this script is run, the following result is obtained.

google Apps script in google docs, how to change a single word to bold inside a paragraph?

Sample script:

Testing:

References: