Bài 12: NodeJS – Utility Module – NodeJS cơ bản

var os = require("os")

var os = require("os"); // In thong tin ve kieu cua OS 
console.log('OS Type la: ' + os.type()); // In thong tin ve OS platform 
console.log('OS Platform : ' + os.platform()); // In thong tin ve tong dung luong bo nho 
console.log('Tong dung luong bo nho : ' + os.totalmem() + " byte."); // In thong tin ve tong dung luong bo nho roi 
console.log('Tong dung luong bo nho roi : ' + os.freemem() + " byte.");

$ node main.js

OS Type la : LinuxOS Platform : linuxTong dung luong bo nho : 25103400960 byte.Tong dung luong bo nho roi : 20676710400 byte.

var path = require("path")

var path = require("path"); // Chuan hoa duong dan voi phuong thuc normalize() 
console.log('Phuong thuc NORMALIZE : ' + path.normalize('/test/test1//2slashes/1slash/tab/..')); // Ket hop cac tham so dau vao de tao mot duong dan 
console.log('Phuong thuc JOIN : ' + path.join('/test', 'test1', '2slashes/1slash', 'tab', '..')); // Resolve mot duong dan tuyet doi 
console.log('Phuong thuc RESOLVE : ' + path.resolve('main.js')); // Lay thong tin cua duoi duong dan 
console.log('Phuong thuc EXTNAME : ' + path.extname('main.js'));

$ node main.js

Phuong thuc NORMALIZE : /test/test1/2slashes/1slashPhuong thuc JOIN : /test/test1/2slashes/1slashPhuong thuc RESOLVE : /web/com/1427176256_27423/main.jsPhuong thuc EXTNAME : .js

var net = require("net")

var net = require('net');
var server = net.createServer(function(connection)
{ console.log('Ket noi voi Client');
connection.on('end', function()
{ console.log('Mat ket noi voi Client'); });
connection.write('Hello World!\r\n'); 
connection.pipe(connection); }); 
server.listen(8080, function() 
{ console.log('Server dang lang nghe'); });

$ node server.js

Server dang lang nghe

var net = require('net'); 
var client = net.connect({port: 8080}, function() 
{ console.log('Da ket noi voi Server!'); }); 
client.on('data', function(data) { console.log(data.toString()); 
client.end(); }); client.on('end', function() 
{ console.log('Mat ket noi voi Server'); });

$ node client.js

Da ket noi voi Server!Hello World!Mat ket noi voi Server

Server dang lang ngheKet noi voi ClientMat ket noi voi Client

var dns = require("dns")

var dns = require('dns'); 
dns.lookup('www.google.com', function onLookup(err, address, family) 
{ console.log('Dia chi:', address); 
dns.reverse(address, function (err, hostnames) 
{ if (err) { console.log(err.stack); } 
console.log('Phuong thuc REVERSE cho dia chi: ' + address + ' thanh mang cac hostname: ' + JSON.stringify(hostnames)); }); });

$ node main.js

Dia chi: 173.194.46.83Phuong thuc REVERSE cho dia chi 173.194.46.83 thanh mang cac hostname: ["ord08s11-in-f19.1e100.net"]

var domain = require("domain")

var domain = require("domain"); var child = domain.create();

var EventEmitter = require("events").EventEmitter; 
var domain = require("domain"); 
var emitter1 = new EventEmitter(); // Tao mot domain boi su dung phuong thuc create() 
var domain1 = domain.create(); 
domain1.on('error', function(err)
{ console.log("domain1 se xu ly loi: ("+err.message+")"); });
 // Them mot Emitter toi domain boi phuong thuc add() 
domain1.add(emitter1); 
emitter1.on('error',function(err)
{ console.log("listener se xu ly loi: ("+err.message+")"); }); 
emitter1.emit('error',new Error('Duoc xu ly boi listener')); 
emitter1.removeAllListeners('error'); 
emitter1.emit('error',new Error('Duoc xu ly boi domain1')); 
var domain2 = domain.create(); domain2.on('error', function(err)
{ console.log("domain2 se xu ly loi: ("+err.message+")"); });
 // Them mot Emitter toi domain boi phuong thuc run() 
domain2.run(function()
{ var emitter2 = new EventEmitter(); 
emitter2.emit('error',new Error('Duoc xu ly boi domain2')); }); 
domain1.remove(emitter1); 
emitter1.emit('error', new Error('Da chuyen doi thanh Exception. He thong bi pha vo!'));

$ node main.js

listener se xu ly loi: (Duoc xu ly boi listener)domain1 se xu ly loi: (Duoc xu ly boi domain1)domain2 se xu ly loi: (Duoc xu ly boi domain2)events.js:72 throw er; // Unhandled 'error' event ^Error: Da chuyen doi thanh Exception. He thong bi pha vo! at Object. (/web/com/1427722220_30772/main.js:40:24) at Module._compile (module.js:456:26) at Object.Module._extensions..js (module.js:474:10) at Module.load (module.js:356:32) at Function.Module._load (module.js:312:12) at Function.Module.runMain (module.js:497:10) at startup (node.js:119:16) at node.js:906:3