3. 无重复字符的最长子串

    var lengthOfLongestSubstring = function (s) {
      let res = 0, i = 0;
      let m = ''
      let temp = [];
      while (i < s.length) {
        if (temp.indexOf(s[i]) === -1) {
          temp.push(s[i]);
        } else {
          temp.shift();
          continue;
        }
        res = res > temp.length ? res : temp.length;
        m = res > temp.length ? m : temp.join('')
        i++;
      }
      return [m, res];
    };
    console.log(lengthOfLongestSubstring('abccdda'));