Node.js
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Node.js is a JavaScript runtime built on Chrome's V8 engine that allows JavaScript to be run on the server-side. It uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, especially for real-time applications with heavy network use. While it shares a language with client-side JavaScript, Node.js is meant for server-side applications and not in the browser.
Node.js
- 2. Interpreted using Google’s V8 JavaScript engine (same one they use in Chrome) Provides some core libraries (network, IO, console, etc.) Supports extensions / modules Is both a runtime environment and a library
- 3. It’s not browser / document JavaScript It’s not jQuery It’s not PHP/Ruby/ASP.NET/other server-side language It’s not Apache / IIS
- 4. Functions are Objects ◦ Passed as arguments into other functions ◦ Similar to Lambdas / Anonymous Methods in .NET ◦ Ajax.oncomplete = function(result) { document.write(result); }; ◦ $.ajax(function(result) { document.write(result); }); Callbacks EVERYWHERE
- 6. Waiting for expensive operations is stupid Single thread event loop ◦ Your code is single-threaded, so you don’t have to deal with any concurrency / shared state / other multi-threaded problems ◦ Expensive “back-end” operations are spawned as separate processes and trigger events and/or call back to your code when they’re finished
- 7. “Everything runs in parallel, except your code” Go read this file Go listen for this message Go download this image K, I’m done Waiting
- 10. (Almost) All interaction is done via events and callbacks If your code relies on multiple async operations to complete, you’ll have to do a bit of call management / abstraction All of “your code” should return very quickly, or create itself as an async object (via EventEmitter)
- 11. “parallel” IO execution allows you to make expensive queries at the same time, increasing efficiency One language to rule them all – server side and client side code for the same web app V8 is one of the fastest script interpreters on the planet Ridiculously fast benchmarks ◦ 600% faster than apache
- 12. 100,000 requests 1,000 concurrent Node Apache / PHP Failed Requests 147 879 Requests/seco 4725.4 823.38 nd 3 Total 211.62 1214.51 ms/request 1 0 Processing time 40 565 (ms)/request Total time (s) 21.162 121.451
- 13. Uses more CPU and RAM on server (only a little more, but more nonetheless) Can get complicated if doing more than one async call per request Lots of node-specific language constructs ◦ require, exports, etc. Uses JavaScript, which in itself has a lot of quirks and fallacies
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