计算字符串中的单词数

function countWords(str) {
  let wordCount = 0;
  let word = '';

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

    if (char.match(/[a-zA-Z0-9]/)) {
      word += char;
    } else if (word !== '') {
      wordCount++;
      word = '';
    }
  }

  if (word !== '') {
    wordCount++;
  }

  return wordCount;
}

const inputString = 'Hello, world! This is a sample string.';
const result = countWords(inputString);
console.log(result); // 输出：7