3-longest-substring-without-repeating-characters.js

/**
 * @param {string} s
 * @return {number}
 */
const lengthOfLongestSubstring = (s) => {
  let max = 0;
  const set = new Set();
  let i = 0;
  let j = 0;

  while (j < s.length && i < s.length) {
    if (!set.has(s[j])) {
      set.add(s[j]);
      j++;
      max = Math.max(max, j - i);
    } else {
      set.delete(s[i]);
      i++;
    }
  }

  return max;
};