node.js 小爬虫 imooc 2016.03.06

爬虫目标：获取http://www.imooc.com/learn/348网页中的章节标题和视频信息。

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

//得到html后，取得章节标题和视频信息
function filterChapters(html) {
    var $ = cheerio.load(html);
    var chapters = $('.chapter');
    var courseData = [];
    
    //遍历每一个章节
    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':[]
        };
        //遍历每一个视频
        videos.each(function(item) {
            var video = $(this).find('.studyvideo');
            var videoTitle = video.text();
            var id = video.attr('href').split('video/')[1];
            
            chapterData.videos.push({
                'title': videoTitle,
                'id':id
            });
        });
                //将每一个章节获取的内容导入课程信息
        courseData.push(chapterData);
    });
    return courseData;
};

//输出结果
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');
        });
    });
};

//获取html文件内容
http.get(url, function(res) {
    var html = '';

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

    res.on('end', function() {
        var courseData = filterChapters(html);
        printCourseInfo(courseData);
    });
}).on('error', function() {
    console.log('error!!');
});