Regex for TODO keyword when passing through a list of directories to get a list of files with TODO keyword (eg. //TODO) but not as variable / string

I'm trying to write an application that looks through a directory and flag out all files (be it in directory or subdirectories) that has the TODO keyword (the one that flashes/highlights in color whenever we code in our code editor [i am using visual studio code]

I have gotten most of the code running, its just the last bit that is puzzling me : because my RegEx accepts 'TODO' as a word block, it picks up even files that has TODO as variable name / string content eg.

var todo = 'TODO' or var TODO = 'abcdefg'

so it is messing up with my test cases. How do we write a robust TODO regex / expression that is able to pick up just the TODO keyword (eg. //TODO or // TODO) and ignore the other use cases (in variables/strings etc) I dont want to hardcode // or anything in the regex as well, as i would prefer it to be cross-language as much as possible (eg. // (single-line) or /* (multi-line) for javascript, # for python etc)

Here is my code:

import * as fs from 'fs'; 
import * as path from 'path';

const args = process.argv.slice(2);
const directory = args[0];

// Using recursion, we find every file with the desired extention, even if its deeply nested in subfolders.
// Returns a list of file paths
const getFilesInDirectory = (dir, ext) => {
  if (!fs.existsSync(dir)) {
    console.log(`Specified directory: ${dir} does not exist`);
    return;
  }

  let files = [];
  fs.readdirSync(dir).forEach(file => {
    const filePath = path.join(dir, file);
    const stat = fs.lstatSync(filePath); // Getting details of a symbolic link of file

    // If we hit a directory, recurse our fx to subdir. If we hit a file (basecase), add it to the array of files
    if (stat.isDirectory()) {
      const nestedFiles = getFilesInDirectory(filePath, ext);
      files = files.concat(nestedFiles);
    } else {
      if (path.extname(file) === ext) {
        files.push(filePath);
      }
    }
  });

  return files;
};



const checkFilesWithKeyword = (dir, keyword, ext) => {
  if (!fs.existsSync(dir)) {
    console.log(`Specified directory: ${dir} does not exist`);
    return;
  }

  const allFiles = getFilesInDirectory(dir, ext);
  const checkedFiles = [];

  allFiles.forEach(file => {
    const fileContent = fs.readFileSync(file);

    // We want full words, so we use full word boundary in regex.
    const regex = new RegExp('\\b' + keyword + '\\b');
    if (regex.test(fileContent)) {
      // console.log(`Your word was found in file: ${file}`);
      checkedFiles.push(file);
    }
  });

  console.log(checkedFiles);
  return checkedFiles;
};

checkFilesWithKeyword(directory, 'TODO', '.js');

Help is greatly appreciated!!