Hack for Angular.js to inject authentication headers based on url and request body (if needed).

gistfile1.js

// It works for v1.1.5.
// It's very fragile, so be careful using it with other versions.
//
// To understand how it works, check this out: https://github.com/angular/angular.js/blob/master/src/ng/httpBackend.js#L26-L31
//
// Tried and failed more elegant solutions:
// - Interceptors. Couldn't get the request body.
// - `transformRequest` for the resource or $http. Couldn't get the body or the URL.

app.config(function ($httpBackendProvider) {
  originalBackend = $httpBackendProvider.$get[3];
  newBackend = function (a,b,c) {
    var originalBackendfunc = originalBackend(a,b,c);
    return function(method, url, post, callback, headers, timeout, withCredentials, responseType) {
      // Do your changes here
      originalBackendfunc(method, url, post, callback, headers, timeout, withCredentials, responseType);
    };
  };
  $httpBackendProvider.$get[3] = newBackend
});