加入cookies就报错了，加载不了页面了？

Question

前端的Ajax代码：

/**
 * Created by Administrator on 2018/4/17.
 */

$(function() {

    var $loginBox = $('#loginBox');
    var $registerBox = $('#registerBox');
    var $userInfo = $('#userInfo');

    //切换到注册面板
    $loginBox.find('a.colMint').on('click', function() {
        $registerBox.show();
        $loginBox.hide();
    });

    //切换到登录面板
    $registerBox.find('a.colMint').on('click', function() {
        $loginBox.show();
        $registerBox.hide();
    });

    //注册
    $registerBox.find('button').on('click', function() {
        //通过ajax提交请求
        $.ajax({
            type: 'post',
            url: '/api/user/register',
            data: {
                username: $registerBox.find('[name="username"]').val(),
                password: $registerBox.find('[name="password"]').val(),
                repassword:  $registerBox.find('[name="repassword"]').val()
            },
            dataType: 'json',
            success: function(result) {
                $registerBox.find('.colWarning').html(result.message);
                if (!result.code) {
                    //注册成功
                    setTimeout(function() {
                        $loginBox.show();
                        $registerBox.hide();
                    }, 1000);
                }

            }
        });
    });

    //登录
    $loginBox.find('button').on('click', function() {
        //通过ajax提交请求
        $.ajax({
            type: 'post',
            url: '/api/user/login',
            data: {
                username: $loginBox.find('[name="username"]').val(),
                password: $loginBox.find('[name="password"]').val()
            },
            dataType: 'json',
            success: function(result) {

                $loginBox.find('.colWarning').html(result.message);

                if (!result.code) {
                    //登录成功
                    setTimeout(function() {
                        window.location.reload();
                    }, 1000);
                }
            }
        })
    })

    //退出
    $('#logout').on('click', function() {
        $.ajax({
            url: '/api/user/logout',
            success: function(result) {
                if (!result.code) {
                    window.location.reload();
                }
            }
        });
    })

})

后端的app.js

/**
 * Created by Administrator on 2018/4/16.
 * 应用程序的启动（入口）文件
 */
//加载express模块
var express = require('express');
//加载模板处理模块
var swig = require('swig');
//加载数据库
var mongoose = require('mongoose');
//加载body-parser，用来处理post提交过来的数据
var bodyParser = require('body-parser');
//加载cookies模块
var cookieParser = require('cookie-parser')
//创建app应用=>NodeHS Http.createServer()
var app = express();

//设置静态文件托管
//当用户访问的url以/public开始，那么直接返回对应__dirname + '/public'下的文件
app.use('/public', express.static(__dirname + '/public'));
// app.use('/static', express.static('public'));

//配置应用模板
//定义当前应用所使用的模板引擎
//第一个参数，模板引擎的名称，同时也是模板文件的后缀，第二个参数表示用于解析处理模板内容的方法
app.engine('html', swig.renderFile);
//设置模板文件存放的目录，第一个参数必须是views，第二个参数是目录
app.set('views', './views');
/*注册所使用的模板引擎，第一个参数必须是view engine，第二个参数和app.engine这个方法中定义的模板引擎的名称（第一个参数）是一致的*/
app.set('view engine', 'html');
//在开发过程中，需要取消模板缓存
swig.setDefaults({cache: false});

//bodyparser设置
app.use( bodyParser.urlencoded({extended:true}) );

app.use( function(req, res, next) {
    req.cookies = new cookieParser(req, res);

    //解析登录用户的cookie信息
    req.userInfo = {};
    if (req.cookies.get('userInfo')) {
        try {
            req.userInfo = JSON.parse(req.cookies.get('userInfo'));

            //获取当前登录用户的类型，是否是管理员
            User.findById(req.userInfo._id).then(function(userInfo) {
                req.userInfo.isAdmin = Boolean(userInfo.isAdmin);
                next();
            })
        }catch(e){
            next();
        }

    } else {
        next();
    }
} );

/*
 * 根据不同的功能划分模块
 * */
app.use('/admin', require('./routers/admin'));
app.use('/api', require('./routers/api'));
app.use('/', require('./routers/main'));

//监听http请求
mongoose.connect('mongodb://localhost:27017/blog',function (err) {
    if(err){
        console.log('数据库连接失败');
    }else{
        console.log('数据库连接成功');
        app.listen(8081);
    }
});
// app.listen(8081);

api.js

/**
 * Created by Administrator on 2018/4/16.
 */

var express = require('express');
var router = express.Router();
var User = require('../models/User');
//统一返回格式
var responseData;

router.use(function (req, res, next) {
    responseData = {
        code: 0,
        message:''
    }

    next();
});
/*
* 用户注册
* 注册逻辑
*
* 1.用户名不能为空
* 2.密码不能为空
* 3.两次输入密码必须一致
* 
* 1.用户名是否已经被注册
*   数据库查询
* */
router.post('/user/register', function (req, res, next) {
    var username = req.body.username;
    var password = req.body.password;
    var repassword = req.body.repassword;


    //用户名是否为空
    if(username == ''){
        responseData.code = 1;
        responseData.message = '用户名不能为空';
        res.json(responseData);
        return;
    }
    //密码不能为空
    if(password == ''){
        responseData.code = 2;
        responseData.message = '密码不能为空';
        res.json(responseData);
        return;
    }
    //   两次输入的密码不一致
    if(password != repassword){
        responseData.code = 3;
        responseData.message = '两次输入的密码不一致';
        res.json(responseData);
        return;
    }


    //用户名是否已经被注册了，如果数据库中存在和我们要注册的用户名同名的数据，表示改用户名已经被注册了
    User.findOne({
        username: username
    }).then(function (userInfo) {
        if( userInfo){
            //表示数据库中有改记录
            responseData.code = 4;
            responseData.message = '用户名已经被注册了'
            res.json(responseData);
            return;
        }
        //保存用户注册的信息到数据库中
        var user = new User({
            username: username,
            password: password
        });
        return user.save();
    }).then(function (newUserInfo) {
        responseData.message = '注册成功';
        res.json(responseData);
    });

});

router.post('/user/login', function (req, res, next) {
    var username = req.body.username;
    var password = req.body.password;

    if( username == ''|| password ==''){
        responseData.code = 1;
        responseData.message = '用户名和密码不能为空';
        res.json(responseData);
        return;
    }

    //查询数据库中相同用户名和密码的记录是否存在，如果存在则登陆成功
    User.findOne({
        username: username,
        password: password
    }).then(function (userInfo) {
        if(!userInfo){
            responseData.code = 2;
            responseData.message = '用户名或密码错误';
            res.json(responseData);
            return;
        }
        //用户名和密码是正确的
        responseData.message = '登录成功';
        responseData.userInfo = {
            _id: userInfo._id,
            username: userInfo.username
        }
        req.cookies.set('userInfo', JSON.stringify({
            _id: userInfo._id,
            username: userInfo.username
        }));
        res.json(responseData);
        return;
    })
});

/*
 * 退出
 * */
router.get('/user/logout', function(req, res) {
    req.cookies.set('userInfo', null);
    res.json(responseData);
});

module.exports = router;

报错问题：

TypeError: req.cookies.get is not a function
    at D:\WorkSpace\WebStorm\project\app.js:42:21
    at Layer.handle [as handle_request] (D:\WorkSpace\WebStorm\project\node_modules\express\lib\router\layer.js:95:5)
    at trim_prefix (D:\WorkSpace\WebStorm\project\node_modules\express\lib\router\index.js:317:13)
    at D:\WorkSpace\WebStorm\project\node_modules\express\lib\router\index.js:284:7
    at Function.process_params (D:\WorkSpace\WebStorm\project\node_modules\express\lib\router\index.js:335:12)
    at next (D:\WorkSpace\WebStorm\project\node_modules\express\lib\router\index.js:275:10)
    at urlencodedParser (D:\WorkSpace\WebStorm\project\node_modules\body-parser\lib\types\urlencoded.js:91:7)
    at Layer.handle [as handle_request] (D:\WorkSpace\WebStorm\project\node_modules\express\lib\router\layer.js:95:5)
    at trim_prefix (D:\WorkSpace\WebStorm\project\node_modules\express\lib\router\index.js:317:13)
    at D:\WorkSpace\WebStorm\project\node_modules\express\lib\router\index.js:284:7
    at Function.process_params (D:\WorkSpace\WebStorm\project\node_modules\express\lib\router\index.js:335:12)
    at next (D:\WorkSpace\WebStorm\project\node_modules\express\lib\router\index.js:275:10)
    at expressInit (D:\WorkSpace\WebStorm\project\node_modules\express\lib\middleware\init.js:40:5)
    at Layer.handle [as handle_request] (D:\WorkSpace\WebStorm\project\node_modules\express\lib\router\layer.js:95:5)
    at trim_prefix (D:\WorkSpace\WebStorm\project\node_modules\express\lib\router\index.js:317:13)
    at D:\WorkSpace\WebStorm\project\node_modules\express\lib\router\index.js:284:7

Answer 1

路由必须写在app.use(cookieparser());
之后才能通过cookie-parser中间件拿到cookie;

var express      = require('express')
var cookieParser = require('cookie-parser')
 
var app = express()
app.use(cookieParser())