Node 常用功能

node.md

Common Node Uses / Node 常用功能

创建 Server

• http

var http = require('http');
http.createServer(function(req, res) {
	res.writeHead(200, {"Content-Type": "text/html"}); // not necessary but better set
	res.end('<div>Hello world!</div>');
}).listen(3000);
console.log('Server has been establish success!');

• express

var express = require('express');
var app = express();
app.get('/', function(req, res) { // The First parameter is request url (without host & port), and if not match can't get access, could be regExp too 
	res.send({
		id: 123,
		name: 'shawn_dongxiaolong'
	}); // automaticly set the Content-Type , don't need to bother about that
}).listen(3000);

创建 WebSocket

• ws 1

/*
 * Server side
 * Methods: ws.send() , ws.on()
 * Events: connection, message, error, close
 * Attributes: wss.clients
 */
// 使用 wss.clients
var WebSocketServer = require('ws').Server;
var wss = new WebSocketServer({
	port: 3000
});
wss.on('connection', function(ws) {
	console.log('someone just coming, now has %d client', wss.clients.length
);
	ws.on('message', function(data) {
		wss.clients.forEach(function(client) {
			client.send(data);
		});
	});
	ws.on('close', function() {
		console.log('someone just leave, now has %d client', wss.clients.length);
	});
	ws.on('error', function(err) {
		console.log(err);
	});
});
console.log('ws estriblish success');

/*
 * Server side
 * Methods: ws.send() , ws.on()
 * Events: connection, message, error, close
 * Attributes: wss.clients
 */
// 不使用 wss.clients

setIncludes(); // if dont support Array.includes then you need this fallback method

var WebSocketServer = require('ws').Server;
var wss = new WebSocketServer({
	port: 3000
});
var clients = [];
wss.on('connection', function(ws) {
	if (!clients.includes(ws)) {
		clients.push(ws);
	}
	console.log('someone just coming, now has %d client', clients.length);

	ws.on('message', function(data) {
		clients.forEach(function(client) {
			client.send(data); // consider it as one room , all clients will be in one room and receive all message
		});
	});
	ws.on('close', function() {
		clients = clients.filter(function(client) {
			return client !== ws;
		});
		console.log('someone just leave, now has %d client', clients.length);
	});
	ws.on('error', function(err) {
		console.log(err);
	});
});
console.log('ws estriblish success');

function setIncludes() {
	if (!Array.prototype.includes) {
		Array.prototype.includes = function(searchElement /*, fromIndex*/ ) {
			'use strict';
			var O = Object(this);
			var len = parseInt(O.length, 10) || 0;
			if (len === 0) {
				return false;
			}
			var n = parseInt(arguments[1], 10) || 0;
			var k;
			if (n >= 0) {
				k = n;
			} else {
				k = len + n;
				if (k < 0) {
					k = 0;
				}
			}
			var currentElement;
			while (k < len) {
				currentElement = O[k];
				if (searchElement === currentElement) { // NaN !== NaN
					return true;
				}
				k++;
			}
			return false;
		};
	}
}

<!-- Client side -->
<meta charset="utf-8">
<form id='form'>
	<label for="name">昵称</label>
	<input id='name' name="name" type="text"></br>
	<label for="msg">消息</label>
	<input id='msg' name='msg' type="text"></br>
	<input type="submit">
</form>
<div id="div"></div>
<script>
/*
 * the WebSocket Object
 * Attributes: onopen, onmessage, onclose, onerror ...
 * Methods: ws.send(), ws.close();
 */
var ws = new WebSocket('ws://127.0.0.1:3000');
var div = getElement('div');

ws.onopen = function() {
	console.log('connection founded successfully!')
};
ws.onmessage = function(e) {
	var data = JSON.parse(e.data);
	div.innerHTML += '<p>' + data.name + ' 说：' + data.msg + '</p>';
};
ws.onerror = function(err) {
	console.log(err);
};
ws.onclose = function() {
	console.log('connection has been closed!')
};

getElement('form').onsubmit = function() {
	ws.send(JSON.stringify({ // must use JSON.stringify & JSON.parse
		name: getElement('name').value,
		msg: getElement('msg').value
	}));
	document.getElementById('name').value = '';
	document.getElementById('msg').value = '';	
	return false;
}

function getElement(id) {
	return document.getElementById(id);
}
</script>

• ws 2

<!-- same as above -->

• socket.io

socket.io 有很多好处，最大的好处是在当客户端不支持websocket的时候有自动的回退方法。缺点是前端也必须引用相应的js文件，使用特定的方法，虽然这些方法也很简单，但终归不能直接使用原生的前端websocket写法
安装socket.io client 的方法： bower install https://github.com/socketio/socket.io-client.git

/* 
 * Server side
 * Methods: socket.on & socket.emit, 
 * Events: connection / connect, disconnect
 */
var http = require('http');
var server = http.createServer().listen(3000);
var io = require('socket.io');
var socketIo = io(server);

/*
 * 如果需要跟client约定一个特殊的路径，则使用如下的配置代替上方的配置
 * var socketIo  = require('socket.io')(3000, { path: '/share'});
 */

socketIo.on('connect', function(client) {
	console.log('someone just coming.')
	client.on('msg', function(data) {
		client.emit('msg', data); // sent it back to this client
		console.log("he said: %s , we do nothing just send it back to him", data);
	})
	client.on('disconnect', function() {
		console.log('someone just leave.');
	})
});
console.log('WebSocketServer established success');

<!-- Client side -->
<meta charset="utf-8">
<form id='form'>
	<label for="name">昵称</label>
	<input id='name' name="name" type="text"></br>
	<label for="msg">消息</label>
	<input id='msg' name='msg' type="text"></br>
	<input type="submit">
</form>
<div id="div"></div>
<script src="bower_components/socket.io-client/socket.io.js"></script>
<script>
/* 
 * Methods: socket.on & socket.emit, 
 * Events: connect, disconnect
 */
var socket = io('http://127.0.0.1:3000');
/*
 * 如果需要跟Server约定一个特殊的路径，则使用如下的配置代替上方的配置
 * var socket = io.connect('http://127.0.0.1:3000', { path: '/share'})
 */
socket.on('connect', function() {
	console.log('connect to 127.0.0.1:3000 success!');
});
socket.on('disconnect', function() {
	console.log('connect just closed');
});

var div = getElement('div');
getElement('form').onsubmit = function() {
	socket.emit('msg', {  // Don't need to JSON.stringify or JSON.parse, socket will automaticly do that work
		name: getElement('name').value,
		msg: getElement('msg').value
	});
	document.getElementById('name').value = '';
	document.getElementById('msg').value = '';	
	console.log(msg)
	return false;
}
socket.on('msg', function(data) {
	console.log(data);
	div.innerHTML += '<p>' + data.name + ' 说：' + data.msg + '</p>';
});

function getElement(id) {
	return document.getElementById(id);
}
</script> 

模块化调用

• js
• json

调用 html文件

• fs

var http = require('http');
var fs = require('fs');
http.createServer(function(req, res) {
fs.readFile('index.html', function(err, html) { 
	if (err) {
		throw err;
	}
	res.writeHead(200, {"Content-Type": "text/html"});  
	res.write(html); // Disadvantages: can't deliver parameters to dynamic change html content
	res.end();
})	
}).listen(3000);

• ejs

// You need 
// 1. Set package.json dependencies include ejs & express 
// 2.npm install 
// 3.your .html file need to rename as .ejs and better put into a floder named 'views'
var express = require('express');
var app = express();

app.set('view engine', 'ejs');

app.get('/', function(req, res) {
	res.render('index', {
		id: 123,
		name: 'shawn_dongxiaolong'
	});
});

app.listen(3000);
console.log('Server establish success, Now open 127.0.0.1:3000 see dose it works!');

<!-- source file： views/index.ejs -->
<div>
<p><%- id %></p>
<p><%- name %></p>
</div>

<!-- open 127.0.0.1:300 and you'll see DOM like below -->
<div>
<p>123</p>
<p>shawn_dongxiaolong</p>
</div>

同步执行

• 函数嵌套
• 递归调用
• step
• sync
• jscex
• promise

var http = require('http');

http.createServer(function(req, res) {
  new Promise(function(resolve, reject) {
    var match = '\/info';
    if (req.url.match(regExp)) {
      resolve();
      return;
    }
    reject('wrong url');
  }).then(function() {
    var msg = 'hello world';
    return msg;
  }).then(function(msg) {
    res.writeHeader('');
    res.end(JSON.stringify({
      status: 200,
      desc: 'success',
      data: msg
    }));
  }).catch(function(err) {
    console.log('error : ', err);
    res.end(err);
  })
}).listen(8888);