title-case second solution is incorrect.

[mades-g]

Given the test case below

...
titleCase('HERE IS MY HANDLE HERE IS MY SPOUT'); // Here Is My Handle Here Is My Spout

function titleCase(str) {
  return str.replace(/\b\w/g, (match) => match.toUpperCase());
}

The solution above only replaces first matched letter and ignores the rest of the letters in a word, assuming that they are all in lowercase.

// a more accurate soltuion would be 
function titleCase(str) {
  return str.replace(/\b\w(\w+)/g, (word, restWord) => `${word[0].toUpperCase()}${restWord.toLowerCase()}`);
}

Explanation

The regex /\b\w(\w+)/g matches the first letter of each word and groups the rest of the letter in a word.

• \b matches the word boundary
• \w matches the first letter of each word
• (\w+) matches more or more letter of each word
• The g flag is used to replace all occurrences of the regex in the string