Find the Length of the Longest Substring without Duplicates

longest-substring-without-duplicates-length.js

var lengthOfLongestSubstring = function(s) {
    let visited = {};
    let maximum = 0;
    let i = 0;
    
    for(let j=0;j<s.length;j++) {        
        
        if(visited[s.charAt(j)] !== undefined) {
            i = Math.max(i, visited[s.charAt(j)])
        }
                
        maximum = Math.max(maximum, (j-i)+1)        
        visited[s.charAt(j)] = j+1;
    }
    
    return maximum;
    
};