最长不重复字符串

function longestNoRepeatStr(str){
    let len = 0
    if(str.length == 0 || str.length == 1){
        return str.length
    }
    for(let i = 0;i < str.length - 1;i++){
        let arr = []
        let item = str[i]
        arr.push(item)
        for(let j = i + 1;j < str.length;j++){
            let jItem = str[j]
            if(arr.indexOf(jItem) == -1){
                arr.push(jItem)
            }else{
                if(arr.length > len){
                    len = arr.length
                }
                break
            }
        }
    }
    return len
}