3 JANUARY 2013 / Mike Brevoort @mbrevoort 

AGENDA Well, it's will be a bit of a hodge podge... My thoughts on Node.js Discuss how I've used it Demo some easy to overlook features 

ME 

ME New York → Delaware/Philadephia → 10th year in Colorado Married 5 Children Coding for 19 years JavaScript, Java, Groovy, C/C++, C#, PHP, Python, XQuery Work @ Pearson Co-organizer of DenverJS 

NODE.JS & ME Met in Spring 2010 Production apps since Winter 2011 Generally an app maker, not a module author 

WHAT WAS THE ATTRACTION? 

WHAT IS IT GOOD FOR? (in my opinion) photo by Joriel "Joz" Jimenez 

GOOD I/O bound programs API aggregation, orchestration, proxying Filtering and data normalization Edge server for client apps Streaming I/O I/O centric systems programming 

WHAT IS IT NOT SO GOOD FOR? (in my opinion) 

BAD LESS GOOD Primarily procedural and serial programs CPU bound tasks Heavy "business logic" Large code bases that "can't" be modularized Very large teams 

OTHERWISE, VERY NICE! 

SOME EXAMPLE USES 

AGGREGATION 

CHATTY CLIENT WITHOUT AGGREGATION 

WITH AGGREGATION 

APP AIR DROP Deep linking, reduce round trips and latency 

STREAMING IMAGE PROCESSING Nothing buffered to disk 

SPINDRIFT Dynamic load balancing and deployment * hoping to open source components early this year 

REALTIME DASHBOARDS Statsd/Graphite inspired by Tasseo 

WEBSOCKETS + FALLBACKS Server Browser Pub Sub (Socket.io) 

FOR EXAMPLE 

NODE.JS EVALUATOR For this presentation Execute inline code snippets in a spawned node.js process Communicate via socket.io between process and browser 

FOR EXAMPLE console.log(process.version); 

THE CLIENT CODE var socket = io.connect(); socket.on('result', function (data) { humane.log(data, { timeout: 5000, clickToClose: true, addnCls: 'humane-bigbox' }) }); function runit(elemId) { socket.emit('run', ['-e', document.getElementById(elemId).textContent]) }

console.log(process.pid);



SERVER CODE var spawn = require('child_process').spawn , express = require('express') , app = express() , server = require('http').createServer(app) , io = require('socket.io').listen(server); app.use(express.static(__dirname + '/../reveal.js')); server.listen(4444); io.sockets.on('connection', function (socket) { socket.on('run', function (data) { runit(data, function (output) { socket.emit('result', output); }) }); }); function runit(options, cb) { var run = spawn('node', options) , output = ""; var append = function (val) { output += val }; run.stdout.on('data', append); run.stderr.on('data', append); run.on('exit', function (code) { if (code !== 0) output += 'EXITED WITH CODE: ' + code; cb(output); }); } 

YOU'RE NOT IN THE BROWSER ANYMORE Fast forward to the future! 

LET'S LOOK AT SOME EASY TO FORGET FEATURES YOU CAN USE TODAY! 

ECMASCRIPT 5 Getters and Setters var obj = { get name() { return this._name }, set name(val) { this._name = val.toUpperCase(); } } obj.name = "mike"; console.log(obj.name); 

ECMASCRIPT 5 Array.prototype Still using underscore.js for this stuff? indexOf(value); lastIndexOf(value) filter(callback) forEach(callback) every(callback) map(callback) some(callback) reduce(callback[, initialValue]) reduceRight(callback[, initialValue]) 

ECMASCRIPT 5 Object.seal(obj) Prevents adding or deleting properties Or changing the descriptors of any property Property values can be changed however var o = { a: 1 }; Object.seal(o); console.log("o is sealed? ", Object.isSealed(o)); o.b = 2; // BOOM 

ECMASCRIPT 5 Object.freeze(obj) Same as seal but properties can't be changed either var o = { a: 1 }; Object.freeze(o); console.log("o is freezed? ", Object.isFrozen(o)); o.a = 2; // BOOM 

ECMASCRIPT 5 Object.create Creates a new object with the specified prototype object and properties var obj = Object.create({x: 10, y: 20}, { z: { value: 30, writable: true }, sum: { get: function() { return this.x + this.y + this.z; } } }); log(obj.x); // 10 log(obj.y); // 20 log(obj.z); // 30 log(obj.sum); // 60 

HARMONY PREVIEW 

V8 HARMONY OPTIONS node --v8-options | grep -A 1 harmony --harmony_typeof (enable harmony semantics for typeof) type: bool default: false --harmony_scoping (enable harmony block scoping) type: bool default: false --harmony_modules (enable harmony modules (implies block scoping )) type: bool default: false --harmony_proxies (enable harmony proxies) type: bool default: false --harmony_collections (enable harmony collections (sets, maps, a nd weak maps)) type: bool default: false --harmony (enable all harmony features (except typeof)) type: bool default: false 

HARMONY COLLECTIONS Maps (and WeakMaps) Harmony Iterators not implemented yet :( var assert = require('assert') , map = new Map() , obj = new Object() , foo = { a: 1 } , bar = { a: 1 }; obj[foo] = 'foo'; assert.equal('foo', obj[foo]); obj[bar] = 'bar'; assert.equal('bar', obj[bar]); assert.equal('bar', obj[foo]); // ??? -> keys converted to strings map.set(foo, 'foo'); assert.equal('foo', map.get(foo)); map.set(bar, 'bar'); assert.equal('bar', map.get(bar)); assert.equal('foo', map.get(foo)); 

HARMONY COLLECTIONS Sets Harmony Iterators not implemented yet :( var assert = require('assert') , set = new Set() , foo = { a: 1 } , bar = { a: 1 } , baz = { a: 1 }; set.add(foo); set.add(bar); assert(set.has(foo)); assert(set.has(bar)); assert(!set.has(baz)); set.delete(foo); assert(!set.has(foo)); assert(set.has(bar)); 

BLOCK SCOPE const let node --harmony --use-strict var assert = require('assert'); const baz = 'baz'; assert.equal('baz', baz); baz = 'new baz'; // BOOM! // SyntaxError: Assignment to constant variable. var assert = require('assert'); { var foo = 'foo'; let bar = 'bar'; } assert.equal('foo', foo); assert.equal('bar', bar); // BOOM! // ReferenceError: bar is not defined 

THANKS! QUESTIONS? Mike Brevoort @mbrevoort