/**
 * @param {string} s
 * @return {number}
 */
var lengthOfLongestSubstring = function(s) {
    if (typeof s !== 'string' || s.length <= 0) return 0;
    let charts = s.split('') // 字符串转数组
    let maxLength = 0
    let leftIndex = 0 // 记录每一次重复的位置
    for (let start = 0; start < charts.length; start++) {
        for (let i = leftIndex; i < start; i++) {
            if (charts[i] == charts[start]) { // 若是有相同的字符串
                maxLength = Math.max(maxLength, start - leftIndex)
                leftIndex = i + 1 // 更新重复位置的下标
                break // 跳出本次循环
            }
        }
    }
    return Math.max(maxLength, charts.length - leftIndex)
};