Why should I use Dependency Injection?

What patterns have emerged for dependency injection in Node.JS?

• Despite how it inspects argument names to resolve it's dependencies, I'm fond of the way AngularJS uses dependency injection to make testing and mocking very convenient. In Node.js however the convention is to require module dependencies privately. Have any recommendable patterns emerged to use dependency injection in Node.js?

• Answer:

  My recommendation would be to be quite explicit. For instance, if your file defines a constructor, make that constructor accept optional parameters that allow overriding the default modules it uses (such as http or fs). Another option is to play with the require method itself. Proxyrequire (https://npmjs.org/package/proxyquire) is a nice solution for that.