LeetCode: First Unique Character In A String Solution

1/**
2 * @param {string} s
3 * @return {number}
4 */
5var firstUniqChar = function (s) {
6  let res = -1
7  for (const c of s) {
8    if (s.indexOf(c) === s.lastIndexOf(c)) {
9      res = s.indexOf(c)
10      break
11    }
12  }
13  return res
14}