longest substring without repeating characters solution

Author: Moonjonghoo

longest-substring-without-repeating-characters/moonjonghoo.js

@@ -0,0 +1,20 @@
+/**
+ * @param {string} s
+ * @return {number}
+ */
+const lengthOfLongestSubstring = function (s) {
+  let longest = 0;
+  let start = 0;
+  const seen = {};
+
+  for (let i = 0; i < s.length; i++) {
+    const char = s[i];
+    if (seen[char] >= start) {
+      start = seen[char] + 1;
+    }
+    seen[char] = i;
+    longest = Math.max(longest, i - start + 1);
+  }
+
+  return longest;
+};