JS - leetcode lengthOfLongestSubstring - https://leetcode.com/problems/longest-substring-without-repeating-characters

lengthOfLongestSubstring.js

var lengthOfLongestSubstring = function(s, len=undefined) {
    // check if all chars same
    if (!len) {
        if (s.length !== 0) {
            const arr = [...s]
            const allEqual = arr => arr.every(val => val === arr[0])

            if (allEqual(arr)) {
                return 1
            }
        }

        if (s.length === 0) {
            return 0
        }

        if (s.length === 1) {
            return 1
        }

        if (s.length === 2) {
            if (s[0] !== s[1]) {
                return 2
            }
            else {
               return 1
           }
        }
    }
     
    var sl = s[0]
    var sls = []
    var tempLength = 0

    if (len && len > tempLength) {
        tempLength = len
    }

    for (var i = 1; i < s.length; i++) {
        while (!sl.includes(s[i])) {
            sl += s[i]
            console.log(s, sl)
        }

        if (sl.includes(s[i+1])) {
            s = s.substr(sl.length, s.length)
            sl = s[0]

            return lengthOfLongestSubstring(s, len=sl.length)
        }
    }
}

//console.log(lengthOfLongestSubstring("pwwkew"))
//console.log(lengthOfLongestSubstring("bbbbb"))
console.log(lengthOfLongestSubstring("pwwkew"))