用javascript编写简单银行取钱存钱流程（函数）

const readline = require('readline-sync')//引用readline-sync
let arr = [['zhang', '123', 2000], ['yang', '123456', 3000]];
//登陆 
let add = function () {
    let s = 2;//输入错误的次数
    while (true) {
        console.log('请输入用户名：');
        let user = readline.question();
        console.log('请输入密码：');
        let password = readline.question();
        for (let i = 0; i < arr.length; i++) {     
            if (user === arr[i][0] && password === arr[i][1]) {
                console.log('欢迎你，登陆成功');
                mean(i);
                return;
            }
        }
        //输入不正确，超过三次
        if (s != 0) {
            console.log(`密码或账户有误，你还有${s}次机会，请重新输入！`);
            s--;

        } else {
            console.log('对不起，账户锁定！');
            break;
        }
    }
}
//存款
let fn1 = function (i) {

    console.log('存款');
    console.log('请输入存款金额：');
    let cunkuan = readline.question() - 0;
    arr[i][2]+= cunkuan;
    console.log('系统正在为你存钱请稍等。。。。。\n存钱成功您当前余额为' + arr[i][2]);
}
//取款
let fn2 = function (i) {
    console.log('取款');
    console.log('请输入取款金额：');
    let qukuan = readline.question() - 0;
    if (qukuan > arr[i][2]) {
        console.log('对不起你的余额不足！，请重新输入金额或者退出');
    } else {
        arr[i][2] = arr[i][2] - qukuan;
        console.log('正在为你取钱。。。。。\n您当前余额为：' + arr[i][2]);
    }
}
//查看
let fn3 = function (i) {
    console.log('查看');
    console.log('正在查询。。。。\n您当前的余额为：' + arr[i][2]);
}

//退出

let fn4 = function () {
    console.log('退出');
    console.log('欢迎你下次使用！');
}

//流程
let mean = function (i) {
    for (let yewu = 1; yewu >= 1; yewu++) {
        console.log('请选择业务：\n1.存款： \n2.取款： \n3.查看： \n4.退出：');
        let yewu = readline.question() - 0;
        switch (yewu) {
            case 1:
                fn1(i);
                continue;
            case 2:
                fn2(i);
                continue;
            case 3:
                fn3(i);
                continue;
            case 4:
                fn4();
                return;
        }break;
    }
}
add();