function upperCase(str)
{
    return str.toUpperCase();
}

function titleCase(str)
{
    // Use regex ^|\s to start at beginning of string or match whitespace in the string. [a-z]/g to match all lowercase letter class globally.
    // Finally return str to all lowercase then replace method applied with previous upperCase function only the first letter.

    var firstLetter = /(^|\s)[a-z]/g;
    return str.toLowerCase().replace(firstLetter, upperCase);
}

console.log(titleCase("HERE IS ALL CAPS"));