AngularJS - How does the DI system know of the name of the arguments?

Question

Example straight from the official site:

function PhoneListCtrl ($scope, $http) {     $http.get('phones/phones.json').success(function(data) {         $scope.phones = data;     });      $scope.orderProp = 'age'; } 

The $scope and $http arguments are unique identifiers for locating corresponding AngularJS services inside the DI system. So how does the DI system retrieve the variable name of these arguments, exactly?

Answer 1

This is the trimmed down version of the way

var FN_ARGS = /^function\s*[^\(]*\(\s*([^\)]*)\)/m; var FN_ARG_SPLIT = /,/; var FN_ARG = /^\s*(_?)(\S+?)\1\s*$/; var STRIP_COMMENTS = /((\/\/.*$)|(\/\*[\s\S]*?\*\/))/mg;  function annotate(fn){     var $inject     if (!($inject = fn.$inject)) {         $inject = [];         fnText = fn.toString().replace(STRIP_COMMENTS, '');         argDecl = fnText.match(FN_ARGS);         angular.forEach(argDecl[1].split(FN_ARG_SPLIT), function(arg){             arg.replace(FN_ARG, function(all, underscore, name){                 $inject.push(name);             });         });         fn.$inject = $inject;     }      return fn.$inject; } 

Demo: Fiddle(See the console);

Steps:
1. Calling toString in the function returns the function source
2. Remove all comments using regex
3. Extract the arguments from the source using regex