Given a string `s`, find the length of the longest substring without repeating characters.

Example 1:

```Input: s = "abcabcbb"
Output: 3
Explanation: The answer is "abc", with the length of 3.
```

Example 2:

```Input: s = "bbbbb"
Output: 1
Explanation: The answer is "b", with the length of 1.
```

Example 3:

```Input: s = "pwwkew"
Output: 3
Explanation: The answer is "wke", with the length of 3.
Notice that the answer must be a substring, "pwke" is a subsequence and not a substring.
```

Example 4:

```Input: s = ""
Output: 0
```

Constraints:

• `0 <= s.length <= 5 * 104`
• `s` consists of English letters, digits, symbols and spaces.

Solutions:

``````/**
* @param {string} s
* @return {number}
*/
var lengthOfLongestSubstring = function(s) {
let n = s.length;
let ans = 0;
let visited = new Map();
for (let i = 0; i < n; i++) {
for (let j = i; j < n ; j++) {
if (visited.has(s[j])) {
visited.clear();
break;
} else {
ans = Math.max(ans, j - i + 1);
visited.set(s[j], true);
}

}

}
return ans;
};``````