Capitalize First Letter code challenges day 3

/**
 * Capitalize the first letter of each word
 * 1) Create an array of words separating by spaces " " with split
 * 2) At each word get the element 0 and capitalize it in a loop
 * 3) Concatenate the words back into a string
 */

function LetterCapitalize(str) {
  var words = str.split(" ");

  // for each index, at the index of words do grab the substring from 0 to 1 (first letter)
  // and uppercase it, the concatenate the rest (from 1 to end with .substring(1)).
  for (var i = 0; i < words.length; i++) {
    words[i] = words[i].substring(0, 1).toUpperCase() + words[i].substring(1);
  }

  return words.join(" ");
}

/* Using Regex*/

function LetterCapitalize2(str) {
  // our regex [a-z] matches every alphabetic character in the string
  // but the \b before it specifies a word boundary, in other words, nothing can
  // come before those letters therefore selecting every word in the string
  return str.replace(/\b[a-z]/gi, function(char) {
    return char.toUpperCase();
  });
}

LetterCapitalize("hello world from coderbyte");

/* Using MAP and Regex*/
function LetterCapitalize(str) {
  return str
    .split(/s+/)
    .map(function(word) {
      return word[0].toUpperCase() + word.slice(1);
    })
    .join(" ");
}

/* Using the string array index */
function LetterCapitalize3(str) {
  var words = str.split(/ /);
  str = "";
  for (var i = 0; i < words.length; i++) {
    // at the current index of words array and first letter ([0]) uppercase it
    // then concat with the rest
    var word = words[i][0].toUpperCase() + words[i].substring(1);
    if (str != "") str += " ";
    str += word;
  }
  // code goes here
  return str;
}

/* Concat */
function LetterCapitalize4(str) {
  // break the string at every space
  return (
    str
      .split(" ")
      // at each mapped item uppercase the first letter
      .map(item =>
        item[0]
          .toUpperCase()
          // concat it slicing from the second letter foward ((1) and re join with ' ' space
          .concat(item.slice(1))
      )
      .join(" ")
  );
}

/* Another one */
function LetterCapitalize(str) {
  let words = str.split(" ");
  for (let i = 0; i < words.length; i++) {
    words[i] =
      words[i].substring(0, 1).toUpperCase() + 
      // pass the length of the word (at index) as the end mark for substring, from 1 to end
      words[i].substring(1, words[i].length); // not sure if passing the second param is needed
  }
  str = words.join(" ");
  return str;
}

/* Another regex */
function LetterCapitalize(str) { 
  return str.replace(/\b(\w)/g, function(match) {return match.toUpperCase()});
}
LetterCapitalize(readline());