node app.js未运行服务器窗口

Question

我正在尝试使用教程创建节点博客，但我一直在布局中遇到错误。我完全复制并粘贴了教程，但仍然没有运气。

layout.jade

extends layout

block content
    h1= title
    #articles
        -each article, i in articles
          div.article
            div.created_at= article.created_at
            div.title 
                a(href="/blog/"+article._id)!= article.title
            div.body= article.body

错误

  

C：\ Users \ pncha_000 \ Documents \ Code \ SimpleBlog \ views \ index.jade：6 4 | h1 =标题5 | #articles＆gt; 6 | - 每篇文章，我在文章7 | div.article 8 | div.created_at = article.created_at 9 | div.title无法读取未定义的属性“长度”

TypeError: C:\Users\pncha_000\Documents\Code\SimpleBlog\views\index.jade:6
    4|     h1= title
    5|     #articles
  > 6|         -each article, i in articles
    7|           div.article
    8|             div.created_at= article.created_at
    9|             div.title 

Cannot read property 'length' of undefined
    at eval (eval at <anonymous> (C:\Users\pncha_000\Documents\Code\SimpleBlog\node_modules\jade\lib\jade.js:172:8), <anonymous>:47:31)
    at eval (eval at <anonymous> (C:\Users\pncha_000\Documents\Code\SimpleBlog\node_modules\jade\lib\jade.js:172:8), <anonymous>:126:4)
    at eval (eval at <anonymous> (C:\Users\pncha_000\Documents\Code\SimpleBlog\node_modules\jade\lib\jade.js:172:8), <anonymous>:139:21)
    at res (C:\Users\pncha_000\Documents\Code\SimpleBlog\node_modules\jade\lib\jade.js:173:38)
    at Object.exports.render (C:\Users\pncha_000\Documents\Code\SimpleBlog\node_modules\jade\lib\jade.js:269:10)
    at Object.exports.renderFile (C:\Users\pncha_000\Documents\Code\SimpleBlog\node_modules\jade\lib\jade.js:305:18)
    at View.exports.renderFile [as engine] (C:\Users\pncha_000\Documents\Code\SimpleBlog\node_modules\jade\lib\jade.js:290:21)
    at View.render (C:\Users\pncha_000\Documents\Code\SimpleBlog\node_modules\express\lib\view.js:76:8)
    at Function.app.render (C:\Users\pncha_000\Documents\Code\SimpleBlog\node_modules\express\lib\application.js:503:10)
    at ServerResponse.res.render (C:\Users\pncha_000\Documents\Code\SimpleBlog\node_modules\express\lib\response.js:802:7)

app.js

var express = require('express');
var path = require('path');
var favicon = require('static-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');

var routes = require('./routes/index');
var users = require('./routes/users');

var app = express();

// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');

app.use(favicon());
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded());
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));

app.use('/', routes);
app.use('/users', users);

/// catch 404 and forward to error handler
app.use(function(req, res, next) {
    var err = new Error('Not Found');
    err.status = 404;
    next(err);
});

/// error handlers

// development error handler
// will print stacktrace
if (app.get('env') === 'development') {
    app.use(function(err, req, res, next) {
        res.status(err.status || 500);
        res.render('error', {
            message: err.message,
            error: err
        });
    });
}

// production error handler
// no stacktraces leaked to user
app.use(function(err, req, res, next) {
    res.status(err.status || 500);
    res.render('error', {
        message: err.message,
        error: {}
    });
});

app.get('/', function(req, res){
  articleProvider.findAll(function(error, docs){
      res.send('index.jade', { locals: {
          title: 'Blog',
          articles:docs
        }
      });
  });
});

module.exports = app;

articleprovider-memory.js

/* 
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
var articleCounter = 1;

ArticleProvider = function(){};
ArticleProvider.prototype.dummyData = [];

ArticleProvider.prototype.findAll = function(callback) {
  callback( null, this.dummyData )
};

ArticleProvider.prototype.findById = function(id, callback) {
  var result = null;
  for(var i =0;i<this.dummyData.length;i++) {
    if( this.dummyData[i]._id == id ) {
      result = this.dummyData[i];
      break;
    }
  }
  callback(null, result);
};

ArticleProvider.prototype.save = function(articles, callback) {
  var article = null;

  if( typeof(articles.length)=="undefined")
    articles = [articles];

  for( var i =0;i< articles.length;i++ ) {
    article = articles[i];
    article._id = articleCounter++;
    article.created_at = new Date();

    if( article.comments === undefined )
      article.comments = [];

    for(var j =0;j< article.comments.length; j++) {
      article.comments[j].created_at = new Date();
    }
    this.dummyData[this.dummyData.length]= article;
  }
  callback(null, articles);
};

/* Lets bootstrap with dummy data */
new ArticleProvider().save([
  {title: 'Post one', body: 'Body one', comments:[{author:'Bob', comment:'I love it'}, {author:'Dave', comment:'This is rubbish!'}]},
  {title: 'Post two', body: 'Body two'},
  {title: 'Post three', body: 'Body three'}
], function(error, articles){});

exports.ArticleProvider = ArticleProvider;