凯撒密码 给文档随机加密

var lower = ‘abcdefghijklmnopqrstuvwxyz‘
var upper = ‘ABCDEFGHIJKLMNOPQRSTUVWXYZ‘

var poem =
`
If by life you were deceived
Don‘t be dismal, don‘t be wild
In the day of grief, be mild
Merry days will come, believe
Heart is living in tomorrow
Present is dejected here
In a moment, passes sorrow
That which passes will be dear
`
// 准备工作 将文档分行 存入数组
var FindRow = function(s) {
    var array = [];
    for (var i = 0; i < s.length; i++) {
        if (upper.includes(s[i])) {
            console.log(`i ${i}`)
            for (var j = i + 1 ; j < s.length; j++) {
                if ((poem[j] == ‘\n‘)) {
                    // 找回车键 切句子
                    console.log(`j ${j}`)
                    var str = s.slice(i,j);
                    console.log(`str ${str}`)
                    array.push(str);
                    //console.log(array)
                    break;
                    // 找到一个 j 之后马上打断 j循环，接着继续 i 循环
                }
            }
        }
    }
    return array;
}
// FindRow(poem) 结果是一个包含 8条 字符串的数组；

// 辅助函数
var find = function(s1,s2) {
    var len = s1.length;
    if (s1.includes(s2)) {
        for (var i = 0; i < len; i++) {
            var str = s1[i];
            if (str == s2) {
                return i;
            }
        }
    }
    return -1;
}
var lowercase1 = function(s) {
    var result = ‘‘;
    for (var i = 0; i < s.length; i++) {
        if (upper.includes(s[i])) {
            var index = find(upper,s[i]);
            result += lower[index];
        } else {
            result += s[i];
        }
    }
    return result;
}
var uppercase1 = function(s) {
    var result = ‘‘;
    for (var i = 0; i < s.length; i++) {
        if (lower.includes(s[i])) {
            var index = find(lower,s[i]);
            result +=  upper[index];
        } else {
            result += s[i];
        }
    }
    return result;
}


// 主函数
var encode = function(s,shift) {
    str = lowercase1(s)
    var result = ‘‘;
    for (var i = 0; i < str.length; i++) {
        if (lower.includes(str[i])) {
            var index = find(lower,str[i]);
            var next = (index + shift) % 26;
            result += lower[next];
        }else {
            result += str[i];
        }
    }
    return result;
}

var encode1 = function(s) {
    var n = FindRow(s);
    var result = ‘‘;
    for (var i = 0; i < n.length; i++) {
　　　　　// 随机 分配 shift
　　　　　var shift =  Math.floor(Math.random() * (25 - 0 + 1) + 0);
        var str = ‘\n‘ + encode(n[i],shift) ;
        // 第一条字符串 i = 0; 重新加在 前面 加上换行符
        result += uppercase1(str);
    }
    return result;
}
encode1(poem)