输入: "Hello, my name is John"
输出: 5
解释: 这里的单词是指连续的不是空格的字符，所以 "Hello," 算作 1 个单词。

const countSegments = function(s) {
  let res = s.match(/\S+/g);
  return res ? res.length : 0;
};

const countSegments = function(s) {
  if (s === '') {
    return 0;
  }
  let count = s[0] === ' ' ? 0 : 1;
  for (let i = 1; i < s.length; i++) {
    if (s[i - 1] === ' ' && s[i] !== ' ') {
      count++;
    }
  }
  return count;
};