javascript uppercase first letter of each word

//capitalize only the first letter of the string. 
function capitalizeFirstLetter(string) {
    return string.charAt(0).toUpperCase() + string.slice(1);
}
//capitalize all words of a string. 
function capitalizeWords(string) {
    return string.replace(/(?:^|\s)\S/g, function(a) { return a.toUpperCase(); });
};function capitalizeFirstLetter(string) {
  return string.charAt(0).toUpperCase() + string.slice(1);
}

console.log(capitalizeFirstLetter('foo bar bag')); // Foofunction titleCase(str) {
   var splitStr = str.toLowerCase().split(' ');
   for (var i = 0; i < splitStr.length; i++) {
       // You do not need to check if i is larger than splitStr length, as your for does that for you
       // Assign it back to the array
       splitStr[i] = splitStr[i].charAt(0).toUpperCase() + splitStr[i].substring(1);     
   }
   // Directly return the joined string
   return splitStr.join(' '); 
}

document.write(titleCase("I'm a little tea pot"));function toTitleCase(str) {
    return str.replace(/\w\S*/g, function(txt){
        return txt.charAt(0).toUpperCase() + txt.substr(1).toLowerCase();
    });
}const str = 'captain picard';

function capitalize(str) {
  return str.charAt(0).toUpperCase() + str.slice(1);
}

const caps = str.split(' ').map(capitalize).join(' ');
caps; // 'Captain Picard'function capitalize(str) {
  const arrOfWords = str.split(" ");
  const arrOfWordsCased = [];

  for (let i = 0; i < arrOfWords.length; i++) {
    const word = arrOfWords[i];
    arrOfWordsCased.push(word[0].toUpperCase() + word.slice(1).toLowerCase());
  }

  return arrOfWordsCased.join(" ");
}