SOURCE

// 滑动窗口方法
function getMaxNoRepeatStr(str) {
    let windowSize = 1;
    let res = str.substring(0, 1)
    let i = 0
    while (windowSize + i <= str.length) {
        if (windowSize > 1) {
            let tempStr = str.substring(i, i + windowSize)
            let tempSet = new Set(tempStr.split(''))
            if (tempSet.size === tempStr.length) {
                res = tempStr
                windowSize++
            } else {
                i++
            }
        } else {
            windowSize++
        }
    }
    return res
}
console.log(getMaxNoRepeatStr('12'))