JavaScript Sliding Window
\nfunction lengthOfLongestSubstring(s) {\n  let seen = new Set();\n  let longest = 0;\n  let l = 0;\n  for (let r = 0; r < s.length; r++) {\n    while (seen.has
```\nfunction lengthOfLongestSubstring(s) {\n  let seen = new Set();\n  let longest = 0;\n  let l = 0;\n  for (let r = 0; r < s.length; r++) {\n    while (seen.has(s[r])) {\n      seen.delete(s[l]);\n      l++;\n    }\n    seen.add(s[r]);\n    longest = Math.max(longest, r - l + 1);\n  }\n  return longest;\n};\n```
['Sliding Window', 'JavaScript']