For vs map/filter/reduce

titlecaseWords.js

const words = ["hello", " ", "world"];

for (let i = 0; i <= words.length; i++) {
  const word = words[i];
  if (word.length <= 0) continue;
  words[i] = uppercaseFirstLetter(word.trim());
}

const titlecasedWords = words
  .filter(isNotEmpty)
  .map(trim)
  .map(uppercaseFirstLetter);