Recently, I went over Dependency Injection to help you understand a simple way to decouple your code a little bit and help your testing out. Sometimes, though, in Node.js a module will depend on a system API provided by Node, which can make it pretty difficult to make sure that private dependency is being used properly. Normal dependency injection doesn’t work in this situation, but don’t give up hope just yet. Continue reading →
Dependency Injection with Node.js
- December 12, 2012
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design patterns, how to, Javascript
Every JavaScript developer knows that events are quite normal in JavaScript and that an event-based system can be quite fun and simple to use. Most even use event mechanisms almost every time they write JavaScript, but have you tried taking it to the extreme? What does it look like when you have an application architecture that rarely has two objects communicating directly with one another? 
When looking through design patterns that help to decouple objects in your applications, one of the simplest techniques to use is dependency injection. This is a common practice in Backbone.js, most notably when assigning models to views, but I haven’t seen it as much as I think I should. Here I’ll be examining what dependency injection is, how it helps, and how I’m putting it to good use in my latest project. 
There are a lot of good books out there, whether they’re novels, references, or they teach you a skill or craft. In the JavaScript world, the book selection can be somewhat limited because it was only until semi-recent years that it took hold as a real language with real applicability, so older books on the subject can be a bit out of the loop. One of the books that treats JavaScript like a real language is Pro JavaScript Design Patterns. 
One of the most widely used design patterns in JavaScript is the module pattern. The module pattern makes use of one of the nicer features of JavaScript – closures – in order to give you some control of the privacy of your methods so that third party applications cannot access private data or overwrite it. In this post I’ll teach you what a closure is, how it works, and how to utilize it to implement the module pattern in your own JavaScript code.