// Created on savesnippets.com · https://savesnippets.com/FaUSOUYn19yWFX
function titleCase(str, skipWords = ['a','an','the','of','in','on','at','to','and','but','or']) {
  return str
    .toLowerCase()
    .split(/\s+/)
    .map((word, i) =>
      i === 0 || !skipWords.includes(word)
        ? word.charAt(0).toUpperCase() + word.slice(1)
        : word
    )
    .join(' ');
}

// Usage
console.log(titleCase('the quick brown fox'));         // The Quick Brown Fox
console.log(titleCase('lord of the rings'));           // Lord of the Rings