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node.js Foundation
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events 事件有两种：

System Events  C Core libuv   

Custom Events  JavaScript Core Event Emitter

一.The node event emitter

1.创建 Emitter module 

新建 emitte.js文件

代码如下

  1. function Emitter(){
  2. this.events = {};
  3. }
  4. // 为事件注册监听器
  5. Emitter.prototype.on = function(type,listener) {
  6. this.events[type] = this.events[type]||[];
  7. this.events[type].push(listener);
  8. };
  10. //发射，something happend, listener responed
  11. Emitter.prototype.emit = function(type){
  12. if (this.events[type]){
  13. this.events[type].forEach(function(listener){
  14.  listener();
  15. })
  16. }
  17. }
  19. module.exports = Emitter;
2.引入emitter 模块
创建app.js 文件
代码如下
  2.  var Emitter = require('./emitter');
  4.  var emtr = new Emitter();
  6.  emtr.on('greet',function(){
  7.  console.log('Somewhere,some said hello.');
  8.  }); //注册事件以及监听器
  10. emtr.on('greet',function(){
  11.  console.log('A greet occured!');
  12. })
  14. emtr.emit('greet');
二.node.js中的events模块
使用nodejs 中的emit 
将上述app.js 改为
  2.  var Emitter = require('events');
  4.  var emtr = new Emitter();
  6.  emtr.on('greet',function(){
  7.  console.log('Somewhere,some said hello.');
  8.  }); //注册事件以及监听器
  10. emtr.on('greet',function(){
  11.  console.log('A greet occured!');
  12. })
  14. emtr.emit('greet');
但是以上使用string 注册事件的方式容易出错
新建config.js文件
代码如下： 
  1. module.exports = {
  2.  events :{
  3.  GREET:'greet',
  4.  FILESAVED:'filesaved'
  5. }
  6. }
现在修改app.js文件如下：
  2.  var Emitter = require('events');
  3.  var eventConfig = require('./config')
  5.  var emtr = new Emitter();
  7.  emtr.on(eventConfig.greet,function(){
  8.  console.log('Somewhere,some said hello.');
  9.  }); //注册事件以及监听器
  11. emtr.on(eventConfig.greet,function(){
  12.  console.log('A greet occured!');
  13. })
  15. emtr.emit(eventConfig.greet);
这样有利于代码的维护升级
三. Object.create prototypes
使用Object.create 生成object 的原型
创建 app.js ,代码如下： 
  1. var person = {
  2.  firstname: '',
  3.  secondname:'',
  4.  greet: function(){
  5. return this.firstname ' ' this.lastname;
  6. }
  7. }
  9. var john = Object.create(person);
  11. john.firstname = 'John'
  12. john.lastname = 'Doe';
  14. var jane = Object.create(person);
  16. jane.firstname = 'Jane';
  17. jane.lastname = 'Doe';
  19. console.log(john.greet());
  20. console.log(jane.greet());
四.Inheriting from event emitter
创建 app.js,使用util模块中的 inherits 来继承原型
代码如下
  1. var EventEmitter = require('events');
  2. var util  = require('util');
  4. function Greeter(){
  5. this.greeting  = 'Hello world!';
  6. }
  8. util.inherits(Greeter,EventEmitter);
  10. Greeter.prototype.greet = function(data){
  11.  console.log('Hello,this is ' data);
  12. this.emit('greet',data);
  13. }
  15. var greeter = new Greeter();
  16. greeter.on('greet',function(data){
  17.  console.log('Hello ,this is an events : ' data);
  18. });
  20. greeter.greet('Tony');
五.ECMAScript 6
literal strings
  2. var name = 'Nike';
  4. var greet = `Hello ${name}`;
  6. console.log(greet);
call and apply
用于改变调用者 this
  1. var obj = {
  2.  name:'John Doe',
  3.  greet: function(){
  4.  console.log(this.name);
  5. }
  6. }
  8. obj.greet.call({name : 'Jane Doe'});
  9. obj.greet.apply({name: 'Jane Doe'});
  2. var util = require('util');
  4. function Person(){
  5. this.firstname = 'John';
  6. this.lastname = 'Doe';
  7. }
  9. Person.prototype.greet = function (){
  10.  console.log('Hello ' this.firstname ' ' this.lastname);
  11. }
  13. function Policeman(){
  14. Person.call(this);//very important 
  15. this.badgenumber = '1234';
  16. }
  17. util.inherits(Policeman,Person);
  19. var pol=  new Policeman();
  20. pol.greet();
Javascript 同步的
Nodejs 异步的
Event Driven No-Blocking I?O in V* javascript
no-blocking : do other things without stopping your programing from running
Buffer
the relationship between buffer and stream
缓冲区 Buffer的使用：
  1. var buf  = new Buffer('Hello','utf8');
  2. console.log(buf);
  3. console.log(buf.toString());
  4. console.log(buf.toJSON());
  5. console.log(buf[2]);
  6. buf.write('wo');
  7. console.log(buf.toString()); //wollo, 会覆盖缓冲区
Files and fs 
ERROR_FIRST CALLBACK: 
callbacks takes an error object as the first parameters;
CHUNK:
 A piece of data sent through  a stream
Data is split in 'chunks'  and streamed
  1. var fs = require('fs');
  2. var greet = fs.readFileSync(__dirname '/greet.txt','utf8');
  4. console.log(greet);
  6. var greet2 = fs.readFile(__dirname '/greet.txt',function(err,data){
  7.  console.log(data.toString());
  8. });
  9. console.log('Done');
things about createWriteStream createReadStream 
  1. var fs = require('fs');
  2. var readable = fs.createReadStream(__dirname '/greet.txt',{encoding: 'utf8',highWaterMark: 16*1024});
  3. var writable = fs.createWriteStream(__dirname '/greatcopy.txt');
  4. readable.on('data',function(chunk){
  5.  console.log(chunk.length);
  6.  writable.write(chunk);
  7. });
pipe 
  1. var fs = require('fs');
  2. var zlib = require('zlib');
  3. var readable = fs.createReadStream(__dirname '/greet.txt' );
  5. var writable = fs.createWriteStream(__dirname '/greatcopy.txt');
  7.  var compressed = fs.createWriteStream(__dirname '/great.txt.gz');
  8.  var gzip = zlib.createGzip();
  10.  readable.pipe(writable);
  12.  readable.pipe(gzip).pipe(compressed);
HTTP_PARSER
  1. var  http = require('http');
  3. http.createServer(function(req,res){
  5.  res.writeHead(200,{'Content-Type':'text/plain'})
  6.  res.end('Hello world\n');
  8. }).listen(1337,'127.0.0.1');
 引入html 文件
  1. var  http = require('http');
  2. var fs = require('fs');
  3. http.createServer(function(req,res){
  5.  res.writeHead(200,{'Content-Type':'text/html'});
  6. var html = fs.readFileSync(__dirname '/index.html');
  7.  res.end(html);
  9. }).listen(1337,'127.0.0.1');
  1. var  http = require('http');
  2. var  fs = require('fs');
  3. http.createServer(function(req,res){
  5.  res.writeHead(200,{'Content-Type':'text/html'});
  6. var html = fs.createReadStream(__dirname '/index.html').pipe(res) 
  8. }).listen(1337,'127.0.0.1');
OutPut  JSON
JSON.stringify(obj)
  1. var  http = require('http');
  2. var  fs = require('fs');
  3. http.createServer(function(req,res){
  5.  res.writeHead(200,{'Content-Type':'application/json'});
  6. var obj = {
  7.  firstname:'John',
  8.  lastname:'Doe'
  9. };
  11.  res.end(JSON.stringify(obj));
  13. }).listen(1337,'127.0.0.1');
Routing: 
mapping  http requests to  contents
  1. var  http = require('http');
  2. var  fs = require('fs');
  3. http.createServer(function(req,res){
  5. if(req.url === '/'){
  6.  fs.createReadStream(__dirname '/index.html').pipe(res);
  7. }
  8. if(res.url === '/api'){
  9.  res.writeHead(200,{'Content-Type':'application/json'});
  10. var obj = {
  11.  firstname:'John',
  12.  lastname:'Doe'
  13. };
  14.  res.end(JSON.stringify(obj));
  15.  }
  17.  res.writeHead(404);
  18.  res.end();
  20. }).listen(1337,'127.0.0.1');
使用 npm 
进入文件夹
npm init ;
npm install moment
发布文件后，删除node_modules后，
使用npm install
                                        --save 添加到package.json 文件中
npm install jasmine-node --save-dev  开发依赖模块
npm install -g nodemon   全局安装
npm update ,更新所有的dependencies
使用别人的代码
  1. var express = require('express');
  3. var app = express();
  5. var port = process.env.PORT || 3000;
  6. app.use('/assets',express.static(__dirname '/public'));
  7. app.use('/',function(req,res,next){
  8.  console.log('Request Url: ' req.url);
  9.  next();
  10. })
  11. app.get('/',function(req,res){
  12.  res.send('<html><head><link href = assets/style.css type =text/css rel = stylesheet /></head><body><h1>Hello world</h1></body></html>');
  13. });
  15. app.get('/person/:id',function(req,res){
  16.  res.send('<html><body><h1> Person: ' req.params.id '</h1></body></html>');
  17. })
  18. app.get('/api',function(req,res){
  19.  res.send('<html><body><h1>Hello world</h1></body></html>')
  20. })
  22. app.listen(port);
  1. var express = require('express');
  3. var app = express();
  5. var port = process.env.PORT || 3000;
  6. app.use('/assets',express.static(__dirname '/public'));
  8. app.set('view engine','ejs')
  10. app.use('/',function(req,res,next){
  11.  console.log('Request Url: ' req.url);
  12.  next();
  13. })
  15. app.get('/person/:id',function(req,res){
  16.  res.render('person',{ID: req.params.id,QStr: req.query.qstr});
  17. })
  19. app.listen(port);
person.ejs:
  1. <html>
  2. <head>
  3. <link href ='assets/styl.css' type = "text/css" ref= "stylesheeet" />
  4. </head>
  5. <body>
  6.  <h1>Peson: <%=ID %> </h1>
  7.  <h2>Query String Value: <%= QStr %> </h2>
  8. </body>
  9. </html>
npm install body-parser
  1. var express = require('express');
  2. var bodyParser = require('body-parser');
  3. var app = express();
  5. var urlencodedParser = bodyParser.urlencoded({extended: false});
  6. var jsonParser = bodyParser.json();
  7. var port = process.env.PORT || 3000;
  8. app.use('/assets',express.static(__dirname '/public'));
  9. app.set('view engine','ejs')
  11. app.get('/',function(req,res){
  12.  res.render('index'); 
  13. })
  15. app.get('/person/:id',function(req,res){
  16.  res.render('person',{ID: req.params.id,QStr: req.query.qstr});
  17. })
  19. app.post('/person',urlencodedParser,function(req,res){
  20.  res.send('Thank You!');
  21.  console.log(req.body.firstname);
  22.  console.log(req.body.lastname);
  23. })
  25. app.post('/personjson',jsonParser,function(req,res){
  26.  res.send('Thank you jsonParser');
  27.  console.log(req.body.firstname);
  28.  console.log(req.body.lastname);
  29. })
  31. app.listen(port);
index.ejs
  1. <html>
  2. <head>
  3. <link href ='/assets/styl.css' type = "text/css" ref= "stylesheeet" />
  4.     <script src = "http://ajax.aspnetcdn.com/ajax/jQuery/jquery-2.1.4.min.js"></script>
  5. </head>
  6. <body>
  7. <h1>Hello World!</h1>
  8. <form method ='POST' action="/person"> 
  9.  First name: <input type ="text" id ="firstname" name ="firstname"/><br>
  10. Last  name: <input type ="text" id= "lastname" name= "lastname"/><br>
  11. <input type ="submit" value ="submit"/>
  12.  </form>
  13.  <script>
  14.  $.ajax({
  15.  type: "POST",
  16.  url: "/personjson",
  17.  data: JSON.stringify({firstname: "John",lastname:"Doe"}),
  18.  dataType: 'json',
  19.  contentType: 'application/json'
  20.  })
  21.  </script>
  22. </body>
  23. </html>
mongoose


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