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Javascript Update May 2013

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A quick look at where Javascript is at in May 2013.

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Javascript Update May 2013

  1. 1. The Javascript UpdateRamesh Nairram@hiddentao.comhttp://twitter.com/hiddentaoWhere Javascript is at - May 2013
  2. 2. What this talk will cover● Javascript history● Language overview● Browser goodies● Front-end ecosystem● Back-end: Node.js● Variations and alternatives, e.g. CoffeeScript● The cutting edge – future stuff● How to stay up-to-date
  3. 3. Evolution● Created in 1995 at Netscape● Mocha → LiveScript → JavaScript● Accepted by ECMA by 1997– ECMAScript is official standard name– Javascript = JScript (Internet Explorer)● v3 (JS 1.5) set the standard● ECMA TC39 working on ES.next, Harmony
  4. 4. Language overview● Built-in types: Boolean, Number, String, null, undefined– Strings are UTF-16● Dynamically typed● Objects work as hash tables– Arrays are also Objects● Functions are Objects– Anonymous/lambda functions– Inner functions, i.e. closures!● Global object: this, window (browsers)– All built-in functions can be overridden● Classes are defined as function– Members and methods– Inheritance via prototypehttp://www.yuiblog.com/crockford/
  5. 5. Browser programming model● Single thread per window– No rendering while executing code– Can have “Web workers” (more on this later)● Event queue– Asynchronous event handling– Most DOM event callbacks● Useful: setTimeout/setInterval– (For animations use requestAnimationFrame)
  6. 6. Browser APIs● window, document, location, navigator● AJAX– Google Maps put this on the map (no pun intended!)● HTML5– tons of stuff● Non-standard / extensions– Mozilla: OpenWebApps, Audio– Others?
  7. 7. AJAX● XMLHttpRequest● JSON, XML, plain text, etc.● Same-origin policy– JSONP work-around● 2-6 simultaneous connections to a host● Comet– Server “pushes” data to browser– e.g. Long-polling
  8. 8. HTML5Media<audio><video>Drag and DropHistoryCanvas2D + WebGL<canvas>Web WorkersServer-sent eventsWeb StorageWeb SocketsFile SystemIndexed DBWeb RTCFullscreen + Page VisibilityBattery + SensorsUser media (camera)
  9. 9. Really exciting● HTML5 Audio + Video● Canvas2D + WebGL– Hardware-accelerated 3D games● Web RTC– Peer-to-peer bi-directional communication● Device sensors + user media– Firefox OS exposes even more● Web Workers– Better than setTimeout/setInterval
  10. 10. Utility libraries● JQuery (~32 KB)– Simplify cross-browser HTML scripting– CDN: jQuery, Google, MS– Alternatives: Prototype, Ext.js, Dojo, MooTools, Script.aculo.us● Lodash/Underscore (~8 KB)– Utility belt, e.g. Array.reduce()● Async (~3 KB)– Simplify asynchronous programming● Many others...
  11. 11. MVC● Object-Oriented design pattern– Ruby-on-Rails, Django, CodeIgniter, etc.● Essential for single-page web apps● Backbone (~6 KB)– Uses events extensively– Models connect to HTML5 storage or server– Controller/View objects handle DOM events– Router handles URLs and History changes● Tons of other frameworks– Angular, Ember, Knockout, Dojo, YUI, many others...http://todomvc.com/
  12. 12. UI frameworks● JQuery UI– JQuery Mobile● Kendo UI (non-free)– Uses jQuery– Kendo Mobile● Wijmo (non-free)– Built on jQuery + jQuery UI● Sencha Ext JS (non-free)– Sencha TouchAlso built on jQuery...● Easy UI● Zino UI● Ignite UI● jQWidgets
  13. 13. Modules and dependencies● Modules are good– Avoid global namespace pollution– Explicitly specify code dependencies● No concept of modules in JS– Coming in future versions● Current work-arounds:– AMD– CommonJS
  14. 14. define([jquery], function( $ ){return {hideIt: function() {$(#myDiv).hide();}};});var $ = require(jquery);module.exports = {hideIt: function() {$(#myDiv).hide();}}● Load-on-demand, with remote loading● RequireJS (~6 KB)● Optimizer which concatenates all intoone fileAMD CommonJS● More natural way of writing a module● Load everything at the start, locally only
  15. 15. Ideally, use both!(function(){// in browser this should be the window objectvar global = this;var myClass = {...}// AMDif (typeof define !== "undefined" && define !== null && define.amd) {define(function() {return myClass;});}// CommonJSelse if (typeof module !== "undefined" && module !== null) {module.exports = myClass;}// Browserelse {global.myClass = myClass;}}());
  16. 16. Building your project...● SCRIPTs loaded one at a time, unlike CSS● How to speed it up?– Minify all scripts● Uglify, Google Closure, YUI Compressor– Concatenate all scripts into one file● RequireJS (AMD), Hem (CommonJS)● Grunt – a make for Javascript● Bower – like apt-get for your Javascript packages● Yeoman = Yo + Grunt + Bower
  17. 17. Back-end scripting● Mozilla Rhino● Ringo JS– Based on Rhino● Node.js– This one has the momentum!
  18. 18. Node.js● Event-driven asynchronous I/O– One thread for app, one for handling I/O● V8 Engine from Chrome● Windows, OS X, Linuxvar http = require(http);http.createServer(function (req, res) {res.writeHead(200, {Content-Type: text/plain});res.end(Hello Worldn);}).listen(1337, 127.0.0.1);console.log(Server running at http://127.0.0.1:1337/);http://nodejs.org/Used by:● Wall Street Journal● Microsoft● eBay● many more...
  19. 19. Node.js community● Node Package Manager (like apt-get)– ~30,000 packages– Almost all on Github, so easy to contribute● Notable packages:– Express JS – MVC framework– Socket.IO – Bi-directional client-server comms.– Mongoose – MongoDB client library– Jade – template language– Grunt – build tool (remember?)http://npmjs.org/
  20. 20. Variations + alternatives● Javascript has many flaws and annoyances● Next version will fix a lot of things– But will still take time to become available acrossall browsers and devices● What can we do today?– CoffeeScript, ClojureScript, TypeScript, Opal– Dart– many others...http://altjs.org/
  21. 21. CoffeeScript● Released in 2009● Looks like Ruby and Python● Great features and shortcuts– Classical inheritance– Loops and comprehensions● Translates 1-on-1 to Javascript● Hard to debug– Unless your IDE can use its source maps● Very popular NPM modulehttp://coffeescript.org/
  22. 22. Account = (customer, cart) ->@customer = customer@cart = cart$(.shopping_cart).bind click, (event) =>@customer.purchase @cartvar Account;Account = function(customer, cart) {var _this = this;this.customer = customer;this.cart = cart;return $(.shopping_cart).bind(click,function(event) {return_this.customer.purchase(_this.cart);});};CoffeeScript JavascriptMore runnable examples on http://coffeescript.org/
  23. 23. Dart● Google released it in 2011– They hope this will replace Javascript in future● Class-based OOP language● Full-stack– Virtual Machine for running on server– Compiles to Javascript for browser● Chromium comes bundled with Dart VM● IDE and SDK available● Still not that popular– Other browser vendors not keen
  24. 24. Dart examplelibrary hi;import dart:html;main() {query(#status).text = Hi, Dart;}<html><head><title>Hi Dart</title></head><body><h2 id="status">Waiting for Dart to start</h2><script type="application/dart" src="hi.dart"></script><scriptsrc="https://dart.googlecode.com/svn/branches/bleeding_edge/dart/pkg/browser/lib/dart.js"></script></body></html>
  25. 25. The cutting edge●ES.Next (ECMAScript 6?)– Modules, Classes– Object.observe(), Proxies– Maps, Sets– Usable today with Harmonzir●Emscripten (Mozilla)– Compile LLVM byte-code to Javascript●C/C++, anyone?●asm.js (Mozilla)– Highly-optimizable ow-level subset– Opt-in: use asm●Unreal Engine demo: http://www.unrealengine.com/html5/– Emscripten + asm.js– Only 2x slower than C++ version●Comparable to Java, C#
  26. 26. Staying up-to-date● DailyJS– http://dailyjs.com/● Badass JS– http://badassjs.com/● Planet Node– http://planetnodejs.com/● Node Up– http://nodeup.com/

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