Phần 12: NodeJS – Utility Module – NodeJS căn bản cho người mới bắt đầu

var os = require("os")

var os = require("os"); // In thong tin ve kieu cua OS 
console.log('OS Type la: ' + os.kind()); // 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 essential.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('/take a look at/test1//2slashes/1slash/tab/..')); // Ket hop cac tham so dau vao de tao mot duong dan 
console.log('Phuong thuc JOIN : ' + path.be a part of('/take a look at', 'test1', '2slashes/1slash', 'tab', '..')); // Resolve mot duong dan tuyet doi 
console.log('Phuong thuc RESOLVE : ' + path.resolve('essential.js')); // Lay thong tin cua duoi duong dan 
console.log('Phuong thuc EXTNAME : ' + path.extname('essential.js'));

$ node essential.js

Phuong thuc NORMALIZE : /take a look at/test1/2slashes/1slashPhuong thuc JOIN : /take a look at/test1/2slashes/1slashPhuong thuc RESOLVE : /internet/com/1427176256_27423/essential.jsPhuong thuc EXTNAME : .js

var web = require("web")

var web = require('web');
var server = web.createServer(operate(connection)
{ console.log('Ket noi voi Client');
connection.on('finish', operate()
{ console.log('Mat ket noi voi Client'); });
connection.write('Hello World!rn'); 
connection.pipe(connection); }); 
server.pay attention(8080, operate() 
{ console.log('Server dang lang nghe'); });

$ node server.js

Server dang lang nghe

var web = require('web'); 
var shopper = web.join({port: 8080}, operate() 
{ console.log('Da ket noi voi Server!'); }); 
shopper.on('knowledge', operate(knowledge)  console.log(knowledge.toString()); 
shopper.finish(); ); shopper.on('finish', operate() 
{ console.log('Mat ket noi voi Server'); });

$ node shopper.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', operate onLookup(err, deal with, household) 
{ console.log('Dia chi:', deal with); 
dns.reverse(deal with, operate (err, hostnames) 
{ if (err) { console.log(err.stack); } 
console.log('Phuong thuc REVERSE cho dia chi: ' + deal with + ' thanh mang cac hostname: ' + JSON.stringify(hostnames)); }); });

$ node essential.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 area = require("area")

var area = require("area"); var youngster = area.create();

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

$ node essential.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)occasions.js:72 throw er; // Unhandled 'error' occasion ^Error: Da chuyen doi thanh Exception. He thong bi pha vo! at Object. (/internet/com/1427722220_30772/essential.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