readme.md

Challenge: Count Vowels

Instructions

Write a function called countVowels that takes in a string and returns the number of vowels in the string.

Function Signature

/**
 * Returns the number of vowels in a string.
 * @param {string} str - The string to search.
 * @returns {number} - The number of vowels in the string.
 */
function countVowels(str: string): number;

Examples

countVowels('hello'); // 2
countVowels('why'); // 0
countVowels('mississippi'); // 4

Constraints

• It shouldn't matter if the input string is uppercase or lowercase

Hints

Solutions

Click For Solution

function countVowels(str) {
  const formattedStr = str.toLowerCase();
  let count = 0;

  for (let i = 0; i < formattedStr.length; i++) {
    const char = formattedStr[i];

    if (
      char === 'a' ||
      char === 'e' ||
      char === 'i' ||
      char === 'o' ||
      char === 'u'
    ) {
      count++;
    }
  }

  return count;
}

Explanation

• Make the string lowercase. This is because we want to count both uppercase and lowercase vowels.
• Create a variable called count and set it to 0. This is the variable we will use to keep track of how many vowels we have found.
• Create a for loop that will loop through each character in the string. We then create a variable called char and set it to the current character in the string.
• Check if the character is a vowel. If it is, we increment count by 1. Once we have looped through the entire string, we return count.

Test Cases

test('Counting vowels in a string', () => {
  expect(countVowels('Hello, World!')).toBe(3);
  expect(countVowels('JavaScript')).toBe(3);
  expect(countVowels('OpenAI Chatbot')).toBe(6);
  expect(countVowels('Coding Challenge')).toBe(5);
});