Node.js
Created by Maksym Tarasenko
Agenda
- Node Basics
- Modules
- NPM
- Async Code / Streams
- Development & Debug
What is node?
- v8 javascript engine
- Event drivin
- Non-blocking standart libraries
- C\C++ adons
- NPM
JavaScript Everywhere
- Code reuse (minimal)
- Same programming culture on client and server
- Lots of JavaScript programmers
Vibrant Community
- 324,000+ packages on npm
- Top corporate sponsors
- Huge wealth of JS code
Sweet Spots
- Real-time/high concurrency apps (I/O Bound)
- API tier for single-page apps and rich clients (iOS, Android)
- Service orchestration
- Working with document (JSON-style) databases
EVENT LOOP
EVENT LOOP
EVENT LOOP
EVENT LOOP
Event Loop
Modules
- Prevents pollution of the global scope
- Module structure
- module.exports
- Caching
Modules: require
var module1 = require('module1');
var module1 = require('./node_modules/module1/index.js');
var module2 = require('./module2');
var module3 = require('../module3');
Modules:
exports.log = function(msg) {
console.log(msg);
}
module.exports = function Loger() {
this.log = function(msg) {
console.log(msg);
}
};
NPM / Yarn
- package.json
- npm init
- npm install
- npm publish
package.json (1)
{
"name": "3_npm_test",
"version": "1.0.0",
"description": "test package",
"main": "main.js",
"scripts": {
"test": "echo \"Error: no test\" && exit 1",
"runMain": "node main.js"
}
}package.json (2)
{
"repository": {
"type": "git",
"url": "git+https://github.com/itmoh/node-mentoring.git"
},
"keywords": [
"node"
],
"author": "maxim tarasenko",
"license": "ISC",
"bugs": {
"url": "https://github.com/itmoh/node-mentoring/issues"
},
"homepage": "https://github.com/itmoh/node-mentoring#readme"
}Streams
- Events
- fs
- http
- stream-adventure
EventEmitter
var EventEmitter = require('events');
var emitter = new EventEmitter();
var listener = (arg) => {console.log(arg);};
emitter.on('test', listener);
setTimeout(function() {
emitter.emit('test', 'Hello world');
emitter.removeListener('test', listener);
emitter.emit('test', 'Hello world');
}, 1000);
Readable Stream
var fs = require('fs');
var readableStream = fs.createReadStream('file.txt');
var data = '';
readableStream.on('data', function(chunk) {
data+=chunk;
});
readableStream.on('end', function() {
console.log(data);
});
Writable Streams
var fs = require('fs');
var readableStream = fs.createReadStream('file1.txt');
var writableStream = fs.createWriteStream('file2.txt');
readableStream.on('data', function(chunk) {
writableStream.write(chunk);
});
duplex, transform streams
a.pipe(b).pipe(a)
a.pipe(b).pipe(c)
Pipe
var writableModuleStream = fs.createWriteStream('module.txt');
var stream = fs.createReadStream('data.csv');
stream.on('readable', onFileRead);
stream.on('end', function() {
writableModuleStream.end();
});
function onFileRead() {
var data = stream.read();
if (data && !writableModuleStream.write(data)) {
stream.removeListener('readable', onFileRead);
writableModuleStream.once('drain', function() {
stream.on('readable', onFileRead);
onFileRead();
});
}
}
fs + http
var http = require('http'),
fs = require('fs');
http.createServer(function(request, response) {
if (req.method === 'POST') {
fs.readFile('./data.csv', 'utf-8', function(err, data) {
response.end(data);
});
} else res.end('send me a POST\n');
}).listen(3000);
Async Code
- Node-style
- Promises (Q)
- Async
- Generators(ES6)
Node-style
var someModule = require('./some_module');
someModule.sum({ x: 1, y: 2 }, function(err, result) {
if (err) {
console.log(err);
return;
}
console.log(result);
});
Promises (Q)
var someModule = require('./some_module');
var qSum = Q.denodeify(someModule.sum);
Q({ x: 1, y: 2 })
.then(qSum)
.then(function(result) {
console.log(result);
})
.catch(function(error) {
console.log(error);
});
Async
var async = require('async');
var someModule = require('./some_module');
async.waterfall([
function(callback) {
callback(null, { x: 1, y: 2 });
},
someModule.sum,
function(result, callback) {
console.log(result);
},
], function (err, result) {
console.log(err);
});
Generators(ES6)
var Q = require('Q');
var co = require('co');
var someModule = require('./some_module');
var qSum = Q.denodeify(someModule.sum);
function* test() {
try {
var result = yield qSum({x: 1, y: 2});
console.log(result);
} catch(err) {
console.log(err);
}
};
co(test);
Development & Debug
- nodemoni, pm2
- node-inspector, --inspect-brk