CC-11: Objects

with Carmen Salas • 2024/10/22

Code Challenge

1. Write a function named charCount that takes in a string and returns an object where the keys are letters in the string and the value of each key is a count of how many times the character appears in the string.

const charCount = (str) => {
  let res = {};
  for (const char of str) {
    // if the key "char" doesn't exist yet,
    // --> set the value to 1
    // otherwise
    // --> +1 to the current value
    res[char] = res[char] ? res[char] + 1 : 1;
  }
  return res;
};

const fellows = "marcy fellows";
console.log(charCount(fellows)); // returns { "m": 1, "a": 1, "r": 1, "c": 1, "y": 1, " ": 1, "f": 1, "e": 1, "l": 2, "o": 1, "w": 1, "s": 1 }

2+3 (BONUS: Refactor into for...off). Write a function named letterCount that takes in a string and returns an object where the keys are letters in the string and the value of each key is a count of how many times the character appears in the string, not including empty spaces.

const letterCount = (str) => {
  let res = {};
  // removes all non-letter characters in the string
  str = str.replaceAll(/[^a-zA-Z]/g, () => "");
  for (const char of str) {
    // if the key "char" doesn't exist yet,
    // --> set the value to 1
    // otherwise
    // --> +1 to the current value
    res[char] = res[char] ? res[char] + 1 : 1;
  }
  return res;
};

const fellows = "marcy fellows";
console.log(letterCount(fellows)); // returns { "m": 1, "a": 1, "r": 1, "c": 1, "y": 1, " ": 1, "f": 1, "e": 1, "l": 2, "o": 1, "w": 1, "s": 1 }

1. Write a function named vowelCount that takes in a string and returns an object where the keys are letters in the given string that are vowels and the value of each vowel key is a count of how many times the character appears in the string.

const vowelCount = (str) => {
  let res = {};
  // finds only vowels, CASE-INSENSITIVE
  str.match(/[aeiou]/gi).forEach((vowel) => {
    // if the key "vowel" doesn't exist yet,
    // --> set the value to 1
    // otherwise
    // --> +1 to the current value
    res[vowel] = res[vowel] ? res[vowel] + 1 : 1;
  });
  return res;
};

const fellows = "marcy fellows";
console.log(vowelCount(fellows)); // returns {"a": 1, "o": 1, "e": 1}