NodeJs模块¶
1.Url模块¶
查看Url构成
url.parse('http://www.baidu.com:7/assa/s=12?from=123&a=node#12')
// output
Url {
protocol: 'http:',
slashes: true,
auth: null,
host: 'www.baidu.com:7',
port: '7',
hostname: 'www.baidu.com',
hash: '#12',
search: '?from=123&a=node',
query: 'from=123&a=node',
pathname: '/assa/s=12',
path: '/assa/s=12?from=123&a=node',
href: 'http://www.baidu.com:7/assa/s=12?from=123&a=node#12' }
生成一个url
url.format({ protocol: 'http:', slashes: true, auth: null, host: 'www.baidu.com:7', port: '7', hostname: 'www.baidu.com', hash: '#12', search: '?from=123&a=node', query: 'from=123&a=node',
pathname: '/assa/s=12', path: '/assa/s=12?from=123&a=node', href: 'http://www.baidu.com:7/assa/s=12?from=123&a=node#12' })
'http://www.baidu.com:7/assa/s=12?from=123&a=node#12'
为URL或 href 插入 或 替换原有的标签
> url.resolve('/one/two/three', 'four')
'/one/two/four'
> url.resolve('/one/two/three', '/four')
'/four'
> url.resolve('http://www.as.com/one/two','/four')
'http://www.as.com/four'
> url.resolve('http://www.as.com/one/two','four')
'http://www.as.com/one/four'
\`url.parse(urlString[, parseQueryString[, slashesDenoteHost]])\`\`
//对于想把query也即查询条件变为字典格式的，则需要设定第二个参数为true
> url.parse('http://www.baidu.com:7/assa/s=12?from=123&a=node#12')
Url {
protocol: 'http:',
slashes: true,
auth: null,
host: 'www.baidu.com:7',
port: '7',
hostname: 'www.baidu.com',
hash: '#12',
search: '?from=123&a=node',
query: 'from=123&a=node',
pathname: '/assa/s=12',
path: '/assa/s=12?from=123&a=node',
href: 'http://www.baidu.com:7/assa/s=12?from=123&a=node#12' }
> url.parse('http://www.baidu.com:7/assa/s=12?from=123&a=node#12',true)
Url {
protocol: 'http:',
slashes: true,
auth: null,
host: 'www.baidu.com:7',
port: '7',
hostname: 'www.baidu.com',
hash: '#12',
search: '?from=123&a=node',
query: { from: '123', a: 'node' },
pathname: '/assa/s=12',
path: '/assa/s=12?from=123&a=node',
href: 'http://www.baidu.com:7/assa/s=12?from=123&a=node#12' }
//对于不清楚http还是https等协议的url，想要解析出host/hostname等就需要追加最后一个参数为true
> url.parse('//imca/learn/node',true)
Url {
protocol: null,
slashes: null,
auth: null,
host: null,
port: null,
hostname: null,
hash: null,
search: '',
query: {},
pathname: '//imca/learn/node',
path: '//imca/learn/node',
href: '//imca/learn/node' }
> url.parse('//imca/learn/node',true,true)
Url {
protocol: null,
slashes: true,
auth: null,
host: 'imca',
port: null,
hostname: 'imca',
hash: null,
search: '',
query: {},
pathname: '/learn/node',
path: '/learn/node',
href: '//imca/learn/node' }
2.querystring模块¶
querystring序列化
第一个参数：字典
> querystring.stringify({name:'gx',course:['a','b'],from:''})
'name=gx&course=a&course=b&from='
第二个参数：连接符
> querystring.stringify({name:'gx',course:['a','b'],from:''},',')
'name=gx,course=a,course=b,from='
第三个参数：将默认的=号替换成相应的字符
> querystring.stringify({name:'gx',course:['a','b'],from:''},',',':')
'name:gx,course:a,course:b,from:'
最后一个参数options，options（可省）传入一个对象，该对象可设置encodeURIComponent这个属性：encodeURIComponent:值的类型为function，可以将一个不安全的url字符串转换成百分比的形式，默认值为querystring.escape()。
querystring反序列化
querystring.stringify(obj,separator,eq,options)
> querystring.parse('name=gx&course=a&course=b&from=')
{ name: 'gx', course: [ 'a', 'b' ], from: '' }
> querystring.parse('name=gx,course=a,course=b,from=',',')
{ name: 'gx', course: [ 'a', 'b' ], from: '' }
> querystring.parse('name:gx,course:a,course:b,from:',',',':')
{ name: 'gx', course: [ 'a', 'b' ], from: '' }
最后一个参数options，可设置最多key,以字典形式传入
>querystring.parse('name:gx,course:a,course:b,from:',',',':',{maxKeys:2})
{ name: 'gx', course: 'a' }
escape对字符串进行编码
> querystring.escape('哈哈')
'%E5%93%88%E5%93%88'
> querystring.unescape('%E5%93%88%E5%93%88')
'哈哈'
3.补充¶
http协议
http客户端发起请求，创建端口
http服务器在端口监听客户端请求
http服务器向客户端返回状态和内容
4.cheerio(爬虫模块)¶
以慕课网视频教程列表为例
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')
var courseData = []
/*
爬出数据格式为
courseData =[
chapterTitle: chapterTitle,
videos: [
{
title:videoTitle,
id:id
}
]
]
*/
chapters.each(function(item) {
var chapter = $(this)
var chapterTitle = chapter.find('h3').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 printCoutseInfo(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() {
var courseData = filterChapters(html)
printCoutseInfo(courseData)
})
}).on('error',function() {
console.log('获取课程数据出错!')
})
5.events模块¶
var EventEmitter = require('events').EventEmitter
var life = new EventEmitter()
life.setMaxListeners(11)
life.on('求安慰', function(who) {
console.log('给' + who + '揉脚')
})
life.on('求安慰', function(who) {
console.log('给' + who + '洗衣')
})
life.on('求安慰', function(who) {
console.log('给' + who + '做饭')
})
life.on('求安慰', function(who) {
console.log('给' + who + '5')
})
life.on('求安慰', function(who) {
console.log('给' + who + '6')
})
life.on('求安慰', function(who) {
console.log('给' + who + '7')
})
life.on('求安慰', function(who) {
console.log('给' + who + '8')
})
life.on('求安慰', function(who) {
console.log('给' + who + '9')
})
life.on('求安慰', function(who) {
console.log('给' + who + '10')
})
life.on('求安慰', function(who) {
console.log('给' + who + '你想累死我啊。。。')
})
life.on('求溺爱', function(who) {
console.log('给' + who + '交工资')
})
life.on('求溺爱', function(who) {
console.log('给' + who + '买衣服')
})
/*---删除监听事件开始---*/
function water(who) {
console.log('给' + who + '倒水')
}
life.on('求安慰', water)
//单个移除
life.removeListener('求安慰', water)
//下面方法不传参，会移除所有事件监听，传参，只会移除某一类的事件函数
life.removeAllListeners('求安慰')
/*---删除监听事件结束---*/
// var hasConforListener = life.emit('求安慰','汉子')
// var hasLoveListener = life.emit('求溺爱','妹子')
// var hasPlayListener = life.emit('求玩坏','汉子')
// console.log(hasConforListener)
// console.log(hasLoveListener)
// console.log(hasPlayListener)
//打印监听事件个数
console.log(life.listeners('求安慰').length)
console.log(EventEmitter.listenerCount(life,'求安慰'))