node--http小爬虫&事件模块

//http小爬虫

var http=require('http')

var cheerio=require('cheerio')

var url='http://www.imooc.com/learn/348'

function filter(html){

    var $=cheerio.load(html);

    var chapters=$('.mod-chapters')

    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('.stydyvideo')

            var videoTitle=video.text()

            chapterData.videos.push({

                title:videoTitle,

            })

        })

        courseData.push(chapterData)

    })

  return courseData

}

http.get(url,function(res){

    var html=''

    res.on('data',function(data){

        html+=data

    })

    res.on('end',function(){

       var data=filter(html);

        console.log(data)

    })

}).on('error',function(){

})

/**

 * Created by Administrator on 2017-07-03.

 */

//事件模块小插曲   对一个事件不要超过10个监听器

var EventEmitter=require('events').EventEmitter

var life=new EventEmitter();

life.on('ddd',function(){

    console.log('55555555')

})

life.on('ddd',function(){

    console.log('6666')

})

function water(){

}

life.listeners('ddd').length//查看事件的个数

EventEmitter.listenerCount(life,'ddd')

//life.removeListener('ddd',water)//删除事件监听

life.emit('ddd')//事件触发

//删除所有的监听事件

life.removeAllListeners()