LC 3. Longest Substring Without Repeating Characters

function lengthOfLongestSubstring(s: string): number {
  let currHash = {}
  let answer = 0
  let leftPointer = 0
  for (let i = 0; i < s.length; i++) {
    if (Number.isInteger(currHash[s[i]]) && currHash[s[i]] >= leftPointer) {
      leftPointer = currHash[s[i]] + 1
    }
    answer = Math.max(answer, i + 1 - leftPointer)
    currHash[s[i]] = i
  }
  return answer
}