计算字符串中的元音个数

function countVowels(str) {
  let count = 0;
  const vowels = ['a', 'e', 'i', 'o', 'u'];

  for (let i = 0; i < str.length; i++) {
    const char = str[i].toLowerCase();
    if (vowels.includes(char)) {
      count++;
    }
  }

  return count;
}

const input = 'Hello World';
const vowelCount = countVowels(input);
console.log(`字符串中的元音个数为：${vowelCount}`);