Vowels and Consonants: FreeCodeCamp Daily Challenge

Introduction

In the FreeCodeCamp daily challenge, we are asked to analyze a string and determine how many vowels and consonants it contains. This exercise is useful for practicing string manipulation, regular expressions, and counting logic in JavaScript.

Problem Statement

Given a string, return an array with the number of vowels and consonants it contains.

• Vowels are: a, e, i, o, u (both uppercase and lowercase)
• Consonants are all alphabetic letters that are not vowels (both uppercase and lowercase)
• Spaces and non-letter characters do not count as vowels or consonants

Example:

Input: "Hello World!"
Output: [3, 7] // 3 vowels (e, o, o) and 7 consonants (H, l, l, W, r, l, d)

Approach & Analysis

The most efficient solution uses regular expressions to identify vowels and consonants in the string. This allows for fast and clear pattern matching, avoiding manual iteration over each character.

Test Cases

Solution

The JavaScript implementation is as follows:

function count(str) {
  const vowels = str.match(/[aeiou]/gi)
  const consonants = str.match(/[b-df-hj-np-tv-z]/gi)
  return [vowels ? vowels.length : 0, consonants ? consonants.length : 0]
}

• Two regular expressions are defined: one for vowels and one for consonants.
• The match() method is used to find all vowels and consonants.
• An array with the respective counts is returned.

Complexity Analysis

• Time complexity: $O(n)$, where $n$ is the length of the string.
• Space complexity: $O(k)$, where $k$ is the number of matches found (vowels and consonants).

Edge Cases & Considerations

• Empty string: returns [0, 0]
• Only symbols or numbers: returns [0, 0]
• Uppercase and lowercase letters are counted equally
• Special characters and spaces are ignored

Reflections & Learnings

This exercise reinforces the use of regular expressions and handling edge cases in strings. The solution is clear and efficient for most practical cases.

Resources

• MDN: String.match()
• MDN: Regular Expressions

💡 Clarity and simplicity in the solution are often the best optimization for counting problems.