I am truly impressed with the elegance of AngularJS and have been studying the source code to fully understand it. In this series I will be studying the Injector module as this is one of the core modules around which the rest of the framework revolves.

In src/auto/injector.js there is a method createInjector. It is this method that kicks off the whole process.

After a bit of setup this method returns an instanceInjector object.


The injector is an object with the following functions:

    return {
      invoke: invoke,
      instantiate: instantiate,
      get: getService,
      annotate: annotate,
      has: function(name) {
        return providerCache.hasOwnProperty(name + providerSuffix) || cache.hasOwnProperty(name);

First we go through these methods in turn.

  • annotate
  • invoke
  • get
  • instantiate

Then we tie it all together by looking closer at the createInjector method to see how the injector is setup and used : the twin injectors

Finally we look into how a module is loaded and the services are registered with the injectors: loadModules