drevil-v2

  // Convert both letter and word to lowercase to make the search case-insensitive

  const lowerCaseWord = word.toLowerCase();

  const lowerCaseLetter = letter.toLowerCase();


  // Use the split() method with the letter as the separator to get an array of substrings separated by the letter

  const substrings = lowerCaseWord.split(lowerCaseLetter);

  // The count of the letter is the number of splits minus one (because there are n-1 spaces between n items)

  return substrings.length - 1;