nodejs API

1、url网址解析
url.parse(urlString[, parseQueryString[, slashesDenoteHost]])
url.format(urlObject)
url.resolve(from, to)
┌─────────────────────────────────────────────────────────────────────────────┐
│ href │
├──────────┬┬───────────┬─────────────────┬───────────────────────────┬───────┤
│ protocol ││ auth │ host │ path │ hash │
│ ││ ├──────────┬──────┼──────────┬────────────────┤ │
│ ││ │ hostname │ port │ pathname │ search │ │
│ ││ │ │ │ ├─┬──────────────┤ │
│ ││ │ │ │ │ │ query │ │
" http: // user:pass @ host.com : 8080 /p/a/t/h ? query=string #hash "
│ ││ │ │ │ │ │ │ │
└──────────┴┴────��──────┴──────────┴──────┴──────────┴─┴──────────────┴───────┘
(all spaces in the "" line should be ignored -- they are purely for formatting)

https://www.baidu.com:8080/api.php?from=1000phone&course=nodejs#test

 1 {
 2 protocol: 'https:',
 3 slashes: true,
 4 auth: null,
 5 host: 'www.baidu.com:8080',
 6 port: '8080',
 7 hostname: 'www.baidu.com',
 8 hash: '#test',
 9 search: '?from=1000phone&course=nodejs',
10 query: { from: '1000phone', course: 'nodejs' },
11 pathname: '/api.php',
12 path: '/api.php?from=1000phone&course=nodejs',
13 href: 'https://www.baidu.com:8080/api.php?from=1000phone&course=nodejs#test' }

执行命令
node
url
url.parse("https://www.baidu.com")
url.parse("https://www.baidu.com:8080/api.php?from=qianfeng&course=node#level")-----query为字符串
url.parse("https://www.baidu.com:8080/api.php?from=qianfeng&course=node#level",true)-----query为对象
url.parse("https://www.baidu.com",true)
url.parse("//www.baidu.com:8080/api.php?from=qianfeng&course=node#level",true)--没有解析到协议和端口号
url.parse("//www.baidu.com:8080/api.php?from=qianfeng&course=node#level",true)--解析到host和port
将之前的解析出来的使用url.format()执行，可以解析出一个url地址
两段url解析成一个url.resolve("http://www.baidu.com","/api/list.php");
2、querystring网址：http://nodejs.cn/api/

 1 querystring.escape(str)
 2 querystring.parse(str[, sep[, eq[, options]]])
 3 querystring.stringify(obj[, sep[, eq[, options]]])
 4 querystring.unescape(str)
 5 
 6 node
 7 querystring
 8 querystring.stringify({name:"qianfeng",course:["nodejs","vue.js"],from:""})
 9 querystring.stringify({name:"qianfeng",course:["nodejs","vue.js"],from:""},",")----设置分隔符
10 querystring.stringify({name:"qianfeng",course:["nodejs","vue.js"],from:""}，",",":")
11 querystring.parse(默认的字符串)
12 
13 querystring.escape({"from":"beijing"}});
14 querystring.escape("北京")

3、http模块

4、http小爬虫
创建一个文件spider.js
网址：https://www.lagou.com

 1 var http = require("http");
 2 var https = require("https");
 3 var url = "https://www.lagou.com";
 4 https.get(url,function(res){
 5  var html="";
 6  res.on("data",function(data){
 7 html+=data;
 8 )
 9 res.on("end",function(){
10 console.log(html);
11 })
12 res.on("error",function(err){
13 console.log(err);
14 })
15 })

引入一个第三方工具
cnpm install cheerio --save-dev
注意：
--save表示安装到本地---项目依赖--dependencies
-dev表示安装到开发依赖----devDependencies---项目上线时不需要开发依赖

 1 var http = require("http");
 2 var https = require("https");
 3 var cheerio = require("cheerio");
 4 var url = "https://www.lagou.com";
 5 function filter(html){
 6 var $ = cheerio.load(html);
 7 var menu = $(".menu_main");
 8 var menuData = [];
 9 menu.each(function(index,value){
10 var menuTitle = $(value).find("h2").text();
11 var menuLists = $(value).find("a");
12 var menulist = [];
13 menuLists.each(function(index,value){
14 menulist.push($(value).text())
15 })
16 menuData.push({menuTitle:menuTitle,menulist:menulist})
17 })
18 return menuData
19 
20 
21 }
22 
23 https.get(url,function(res){
24 var html="";
25 res.on("data",function(data){
26 html+=data;
27 )
28 res.on("end",function(){
29 console.log(html);
30 var result = filter(html);
31 printMenu(result);
32 })
33 res.on("error",function(err){
34 console.log(err);
35 })
36 })
37 
38 function printMenu(menu){
39 menu.forEach(function(value){
40 console.log(value.menuTitle+"
");
41 value.menuList.forEach(function(value){
42 console.log(value);
43 }
44 )
45 })
46 }

5、request方法
新建文件requestGet.js https://developers.douban.com/wiki/?title=movie_v2#top250
请求的数据http://api.douban.com/v2/movie/top250
http://json.cn/

 1 const https = require('https')
 2 var options = {
 3 hostname: 'api.douban.com',
 4 port: 443,
 5 method: 'GET',
 6 path: '/v2/movie/top250'
 7 }
 8 var responseData = ''
 9 var request = https.request(options, (response) => {
10 // console.log(response)
11 // console.log(response.statusCode)
12 // console.log(response.headers)
13 response.setEncoding('utf8')
14 response.on('data', (chunk) => {
15 responseData += chunk
16 })
17 response.on('end', () => {
18 JSON.parse(responseData).subjects.map((item) => {
19 console.log(item.title)
20 })
21 })
22 })
23 
24 request.on('error', (error) => {
25 console.log(error)
26 })
27 
28 request.end()

新建文件requestPost.js

 1 const http = require('http')
 2 const querystring = require('querystring')
 3 
 4 var postData = querystring.stringify({
 5 'question[title]':'这个视频不错2',
 6 'question[content]':'<p>赞一个</p>',
 7 'question[courseId]':'227',
 8 'question[lessonId]':'1753',
 9 '_csrf_token':'32b0e1e07c657000e1f7250cdeac0377e6af688f'
10 })
11 
12 var options = {
13 hostname: 'www.codingke.com',
14 port: 80,
15 method: 'POST',
16 path: '/ajax/create/course/question',
17 headers: {
18 'Accept':'*/*',
19 'Accept-Encoding':'gzip, deflate',
20 'Accept-Language':'zh-CN,zh;q=0.8,en;q=0.6',
21 'Connection':'keep-alive',
22 'Content-Length': postData.length,
23 'Content-Type':'application/x-www-form-urlencoded; charset=UTF-8',
24 'Cookie':'PHPSESSID=qsqkoo0bq1grc6a5jo7kgk5tn7; CNZZDATA1256018185=1839628736-1476447839-null%7C1485424829; Hm_lvt_9f92046de4640f3c08cf26535ffdd93c=1485410187,1485420976; Hm_lpvt_9f92046de4640f3c08cf26535ffdd93c=1485426828',
25 'Host':'www.codingke.com',
26 'Origin':'http://www.codingke.com',
27 'Referer':'http://www.codingke.com/v/398-chapter-227-course',
28 'User-Agent':'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.95 Safari/537.36',
29 'X-CSRF-Token':'32b0e1e07c657000e1f7250cdeac0377e6af688f',
30 'X-Requested-With':'XMLHttpRequest'
31 }
32 }
33 
34 var request = http.request(options, (res) => {
35 console.log('Status:' + res.statusCode)
36 console.log('headers:' + JSON.stringify(res.headers))
37 res.setEncoding('utf8')
38 res.on('data', (chunk) => {
39 console.log(chunk)
40 })
41 res.on('end', () => {
42 console.log('技术问答提交完毕！')
43 })
44 })
45 
46 request.on('error', (error) => {
47 console.log(error)
48 })
49 
50 request.write(postData)
51 
52 request.end()

7、event事件
events
使用事件：EventEmitter
事件的参数
只执行一个的事件监听器

创建一个文件event_emitter.js

1 const EventEmitter = require('events')
2 class Player extends EventEmitter {}
3 var player = new Player()
4 player.once('play', (track) => {
5 console.log(`正在播放:《${track}》`)
6 })
7 player.emit('play', '精绝古城')
8 player.emit('play', '黄皮子坟')

8、File System
得到文件与目录的信息：stat
创建一个目录：mkdir
创建文件并写入内容：writeFile,appendFile
读取文件的内容：readFile
列出目录的东西：readdir
重命名目录或文件：rename
删除目录与文件：rmdir,unlink

创建fs_1.js---查看状态

const fs = require('fs')

fs.stat('hello.js', (error, stats) =>{
if(error){
console.log(error)
} else {
console.log(stats)
console.log(`文件：${stats.isFile()}`)
console.log(`目录：${stats.isDirectory()}`)
}
})

创建fs_2.js---创建目录

const fs = require('fs')
fs.mkdir('logs', (error) => {
if(error){
console.log(error)
} else {
console.log('成功创建目录：logs')
}
})

创建fs_3.js---写入文件

 1 const fs = require('fs')
 2 fs.writeFile('logs/hello.log', '您好 ~ 
', (error) => {
 3 if(error) {
 4 console.log(error)
 5 } else {
 6 console.log('成功写入文件')
 7 }
 8 })
 9 
10 fs.appendFile('logs/hello.log', 'hello ~ 
', (error) => {
11 if(error) {
12 console.log(error)
13 } else {
14 console.log('成功写入文件')
15 }
16 })

创建fs_4.js---读取文件

1 const fs = require('fs')
2 fs.readFile('logs/hello.log', 'utf8', (error, data) =>{
3 if (error) {
4 console.log(error)
5 } else {
6 console.log(data)
7 }
8 })

创建fs_5.js---读取文件夹

1 const fs = require('fs')
2 fs.readdir('logs', (error, files) => {
3 if (error) {
4 console.log(error)
5 } else {
6 console.log(files)
7 }
8 })

创建fs_6.js--文件重命名

1 const fs = require('fs')
2 fs.rename('logs/hello.log', 'logs/greeting.log', (error) =>{
3 if (error) {
4 console.log(error)
5 } else {
6 console.log('重命名成功')
7 }
8 })

创建fs_7.js--删除目录

 1 const fs = require('fs')
 2 fs.readdirSync('logs').map((file) => {
 3 fs.unlink(`logs/${file}`, (error) => {
 4 if (error) {
 5 console.log(error)
 6 } else {
 7 console.log(`成功的删除了文件: ${file}`)
 8 }
 9 })
10 })
11 
12 fs.rmdir('logs', (error) =>{
13 if (error) {
14 console.log(error)
15 } else {
16 console.log('成功的删除了目录：logs')
17 }
18 })

9、Stream
读取文件流
可读流的事件
可写的文件流
pipe
链式使用 pipe

创建文件stream.js

 1 const fs = require('fs')
 2 var fileReadStream = fs.createReadStream('data.json')
 3 var fileWriteStream = fs.createWriteStream('data-1.json')
 4 var count = 0
 5 fileReadStream.once('data', (chunk) => {
 6 console.log(chunk.toString())
 7 fileWriteStream.write(chunk)
 8 })
 9 fileReadStream.on('data', (chunk) => {
10 console.log(`${ ++count } 接收到：${chunk.length}`)
11 fileWriteStream.write(chunk)
12 })
13 fileReadStream.on('end', () => {
14 console.log('--- 结束 ---')
15 })
16 fileReadStream.on('error', (error) => {
17 console.log(error)
18 })

流的操作

1 const fs = require('fs')
2 var fileReadStream = fs.createReadStream('data.json')
3 var fileWriteStream = fs.createWriteStream('data-1.json')
4 fileReadStream
5 .pipe(fileWriteStream)

进一步处理---写入之前进行压缩

 1 const fs = require('fs')
 2 const zlib = require('zlib')
 3 
 4 var fileReadStream = fs.createReadStream('data.json')
 5 var fileWriteStream = fs.createWriteStream('data.json.gz')
 6 
 7 fileWriteStream.on('pipe', (source) => {
 8 console.log(source)
 9 })
10 
11 fileReadStream
12 .pipe(zlib.createGzip())
13 .pipe(fileWriteStream)