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Node.js, CoffeeScript & Real-Time Web
Jakub Nesetril
[email protected]@jakubnesetril
čtvrtek, 30. června 2011
About Me
web developer for 15 years
director of frontend engineering, GoodData
CEO/founder of apiary.io - hosted REST API tools
čtvrtek, 30. června 2011
Contents
not a deep-dive
aims to explain a bit of the frenzy
really more about Javascript
čtvrtek, 30. června 2011
čtvrtek, 30. června 2011
What is Node.js
• it’s NOT a framework: but several Rails/Sinatra-style frameworks are available for it
• it’s not a programming language: uses Javascript
• it’s not a VM: uses Chrome’s v8 engine)
čtvrtek, 30. června 2011
What is Node.js
• clever glue code between C and Javascript, with standard libraries
• exposes low-level POSIX to JS
• advanced TCP/HTTP support
• strongly event-oriented(reactor pattern)
• fast
čtvrtek, 30. června 2011
#3 on Github
more traffic then jQuery
Popular
čtvrtek, 30. června 2011
Getting Started—installing Node
Node changes quickly, use nvm or n to install:
https://github.com/creationix/nvmhttps://github.com/visionmedia/n
Allows to quickly migrate between version:
$ nvm ls … stable: v0.4.8-rc latest: v0.4.8-rc current: v0.4.6$ nvm install 0.4.8-rc»»» downloads, builds, installs and sym-links new node
čtvrtek, 30. června 2011
Getting Started—installing libraries
NPM - Node Package Manager
$ curl http://npmjs.org/install.sh | sh…$ npm install foo
Debugging:
$ npm install -g node-inspector$ npm install v8-profiler
interactive debugger, breakpoints, inspection of stack variables,memory snapshosts, cpu profiling…
čtvrtek, 30. června 2011
Getting Started—working
Node loads code at startup
Restart required when code changes (unlike PHP, similar to Ruby)
$ npm install -g supervisor
Supervisor watches/restarts your app when changed:
$ supervisor --watch . server.js … DEBUG: crashing child DEBUG: Starting child process with 'node server.js' …
čtvrtek, 30. června 2011
Demo
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Javascript
čtvrtek, 30. června 2011
Javascript
čtvrtek, 30. června 2011
“The World's Most MisunderstoodProgramming Language”
Douglas Crockford, the Yoda of Javascript
čtvrtek, 30. června 2011
čtvrtek, 30. června 2011
Javascript as a Compilation Target
GWT (Google), ObjectiveJ (Cappuccino/280North), everything else…
Different idioms then Javascript
Obscure integration with other Javascript
Unreadable output:
function g(){var a=G(db);if(a!=null){return a}return Q}function i(){var a;if(typeof isBodyLoaded==gb||!isBodyLoaded()){var b=hb;var c;n.write(ib+b+jb);c=n.getElementById(b);a=c&&c.previousSibling;while(a&&a.tagName!=kb){a=a.previousSibling}if(c){c.parentNode.removeChild(c)}if(a&&a.src){return e(a.src)}}return Q}
čtvrtek, 30. června 2011
čtvrtek, 30. června 2011
Compiles to clean Javascript
čtvrtek, 30. června 2011
CoffeeScript
Exposes only The Good Parts™ of Javascript
Syntactic sugar = Less noise, more readable output
Somewhere between Python and Ruby:
• whitespace/indentation defines blocks• classes! inheritance!• default arguments, splats… (catch-all argument)• list comprehensions• destructuring assignments (pattern matching)• auto local-scoped variables (no more manual var)• optional binding of this scope• and many more…
čtvrtek, 30. června 2011
Popular
63% 12%
25%
CoffeeScript plan CoffeeScript JavaScript
Hacker News Poll, June 22ndhttp://news.ycombinator.com/item?id=2683372
čtvrtek, 30. června 2011
Getting Started—installing
$ npm install -g coffee-script
$ coffee server.coffee
$ coffee --compile server.coffee»» produces server.js
$ coffeecoffee>
čtvrtek, 30. června 2011
Common Problems
you’ll end up debugging in Javascript, know how stuff compiles!
isnt is not is not
console.log(1 isnt false)console.log(1 is not false)
in vs of
console.log(x) for x in {a: “a”, b: “b”}console.log(x) for x of {a: “a”, b: “b”}
tricky local vs. global variable scope
čtvrtek, 30. června 2011
Real-Time Web
čtvrtek, 30. června 2011
Traditional Model
Request/Response
The way HTTP was designed
Dramatic benefits for scaling and simplicity
čtvrtek, 30. června 2011
Real-Time Web
Needs bi-directional communication (polling too slow)
WebSocket standard in process, varying support in new browsers
Older browsers can use flash fallback or “long-polling” mechanisms
Requires support from ground-up across the whole backend stack (proxies, web servers, application servers)
čtvrtek, 30. června 2011
Solutions
• Pusher (WebSocket IaaS)
similar to Apple iOS push notification service
keep your existing code/infrastructure
send HTTP POST request to Pusher to push messages
• socket.io
$ npm install socket.io
implements websocket server AND client
transparently supports all fallback mechanisms (many!)
supports IE5.5+, WebKit on iOS/Android/WebOS
čtvrtek, 30. června 2011
Demos
čtvrtek, 30. června 2011
Questions?
čtvrtek, 30. června 2011
