写在前面：

• 安装Node.js和npm不再赘述
• 使用http模块机cheerio模块实现
• 在安装cheerio之前必须安装express及相关组建
  npm install express -gd
  然后再安装cheerio
  npm install cheerio

Code:

var http = require('http');
var cheerio = require('cheerio');
var url = 'http://www.imooc.com/learn/348';

function filterChapters(html) {
    var $ = cheerio.load(html);
    var chapters = $('.chapter');

    // [{
    //     chapterTitle : '',
    //     videos : [
    //         title : '',
    //         id : ''
    //     ]
    // }]

    var courseData = [];
    chapters.each(function(item) {
        var chapter = $(this);
        var chapterTitle = chapter.find('strong').text();
        var videos = chapter.find('.video').children('li');
        var chapterData = {
            chapterTitle : chapterTitle,
            videos : []
        }

        videos.each(function(item) {
            var video = $(this).find('.J-media-item');
            var videoTitle = video.text();
            var id = video.attr('href').split('video/')[1];

            chapterData.videos.push({
                title : videoTitle,
                id : id
            })
        })
        courseData.push(chapterData);
    })
    return courseData;
}

function printCourseInfo(courseData) {
    courseData.forEach(function(item) {
        var chapterTitle = item.chapterTitle;

        console.log(chapterTitle + '\n');
        item.videos.forEach(function(video) {
            console.log('[' + video.id + ']' + video.title + '\n');
        })
    })
}

http.get(url, function(res) {
    var html = '';

    res.on('data', function(data) {
        html += data;
    })

    res.on('end', function() {
        // console.log(html);
        var courseData = filterChapters(html);
        printCourseInfo(courseData);
    })
}).on('error', function() {
        console.log("获取课程数据出错!");
})

用node跑一下可看到结果：

http小爬虫