feat($jsonpCallbacks): new service to abstract how JSONP callbacks are handled

You can now override this service if you have specific requirements about
the behaviour and formatting of the JSON_CALLBACK that is sent to the server
for `$http.jsonp` requests.

Closes #14795

Author: petebacondarwin

angularFiles.js

@@ -28,6 +28,7 @@ var angularFiles = {
     'src/ng/httpBackend.js',
     'src/ng/interpolate.js',
     'src/ng/interval.js',
+    'src/ng/jsonpCallbacks.js',
     'src/ng/locale.js',
     'src/ng/location.js',
     'src/ng/log.js',

src/AngularPublic.js

@@ -77,6 +77,7 @@
   $HttpParamSerializerJQLikeProvider,
   $HttpBackendProvider,
   $xhrFactoryProvider,
+  $jsonpCallbacksProvider,
   $LocationProvider,
   $LogProvider,
   $ParseProvider,
@@ -239,6 +240,7 @@ function publishExternalAPI(angular) {
         $httpParamSerializerJQLike: $HttpParamSerializerJQLikeProvider,
         $httpBackend: $HttpBackendProvider,
         $xhrFactory: $xhrFactoryProvider,
+        $jsonpCallbacks: $jsonpCallbacksProvider,
         $location: $LocationProvider,
         $log: $LogProvider,
         $parse: $ParseProvider,

src/ng/jsonpCallbacks.js

@@ -0,0 +1,83 @@
+'use strict';
+
+/**
+ * @ngdoc service
+ * @name $jsonpCallbacks
+ * @requires $window
+ * @description
+ * This service handles the lifecycle of callbacks to handle JSONP requests.
+ * Override this service if you wish to customise where the callbacks are stored and
+ * how they vary compared to the requested url.
+ */
+var $jsonpCallbacksProvider = function() {
+  this.$get = ['$window', function($window) {
+    var counter = 0;
+    $window.angular.callbacks = {};
+    var callbackMap = {};
+
+    function createCallback(callbackId) {
+      var callback = function(data) {
+        callback.data = data;
+        callback.called = true;
+      };
+      callback.id = callbackId;
+      return callback;
+    }
+
+    return {
+      /**
+       * @ngdoc method
+       * @name $jsonpCallbacks#createCallback
+       * @param {string} url the url of the JSONP request
+       * @returns {string} the callback path to send to the server as part of the JSONP request
+       * @description
+       * {@link $httpBackend} calls this method to create a callback and get hold of the path to the callback
+       * to pass to the server, which will be used to call the callback with its payload in the JSONP response.
+       */
+      createCallback: function(url) {
+        var callbackId = '_' + (counter++).toString(36);
+        var callbackPath = 'angular.callbacks.' + callbackId;
+        var callback = createCallback(callbackId);
+        callbackMap[callbackPath] = $window.angular.callbacks[callbackId] = callback;
+        return callbackPath;
+      },
+      /**
+       * @ngdoc method
+       * @name $jsonpCallbacks#wasCalled
+       * @param {string} callbackPath the path to the callback that was sent in the JSONP request
+       * @returns {boolean} whether the callback has been called, as a result of the JSONP response
+       * @description
+       * {@link $httpBackend} calls this method to find out whether the JSONP response actually called the
+       * callback that was passed in the request.
+       */
+      wasCalled: function(callbackPath) {
+        return callbackMap[callbackPath].called;
+      },
+      /**
+       * @ngdoc method
+       * @name $jsonpCallbacks#getResponse
+       * @param {string} callbackPath the path to the callback that was sent in the JSONP request
+       * @returns {*} the data received from the response via the registered callback
+       * @description
+       * {@link $httpBackend} calls this method to get hold of the data that was provided to the callback
+       * in the JSONP response.
+       */
+      getResponse: function(callbackPath) {
+        return callbackMap[callbackPath].data;
+      },
+      /**
+       * @ngdoc method
+       * @name $jsonpCallbacks#removeCallback
+       * @param {string} callbackPath the path to the callback that was sent in the JSONP request
+       * @description
+       * {@link $httpBackend} calls this method to remove the callback after the JSONP request has
+       * completed or timed-out.
+       */
+      removeCallback: function(callbackPath) {
+        var callback = callbackMap[callbackPath];
+        delete $window.angular.callbacks[callback.id];
+        delete callbackMap[callbackPath];
+      }
+    };
+  }];
+};

test/ng/jsonpCallbacksSpec.js

@@ -0,0 +1,73 @@
+'use strict';
+
+describe('$jsonpCallbacks', function() {
+
+  beforeEach(module(function($provide) {
+    // mock out the $window object
+    $provide.value('$window', { angular: {} });
+  }));
+
+  describe('createCallback(url)', function() {
+
+    it('should return a new unique path to a callback function on each call', inject(function($jsonpCallbacks) {
+      var path = $jsonpCallbacks.createCallback('http://some.dummy.com/jsonp/request');
+      expect(path).toEqual('angular.callbacks._0');
+
+      path = $jsonpCallbacks.createCallback('http://some.dummy.com/jsonp/request');
+      expect(path).toEqual('angular.callbacks._1');
+
+      path = $jsonpCallbacks.createCallback('http://some.dummy.com/jsonp/request');
+      expect(path).toEqual('angular.callbacks._2');
+
+      path = $jsonpCallbacks.createCallback('http://some.dummy.com/jsonp/request');
+      expect(path).toEqual('angular.callbacks._3');
+    }));
+
+    it('should add a callback method to the $window.angular.callbacks collection on each call', inject(function($window, $jsonpCallbacks) {
+      $jsonpCallbacks.createCallback('http://some.dummy.com/jsonp/request');
+      expect($window.angular.callbacks._0).toEqual(jasmine.any(Function));
+
+      $jsonpCallbacks.createCallback('http://some.dummy.com/jsonp/request');
+      expect($window.angular.callbacks._1).toEqual(jasmine.any(Function));
+
+      $jsonpCallbacks.createCallback('http://some.dummy.com/jsonp/request');
+      expect($window.angular.callbacks._2).toEqual(jasmine.any(Function));
+
+      $jsonpCallbacks.createCallback('http://some.dummy.com/jsonp/request');
+      expect($window.angular.callbacks._3).toEqual(jasmine.any(Function));
+    }));
+  });
+
+
+  describe('wasCalled(callbackPath)', function() {
+
+    it('should return true once the callback has been called', inject(function($window, $jsonpCallbacks) {
+      var path = $jsonpCallbacks.createCallback('http://some.dummy.com/jsonp/request');
+      expect($jsonpCallbacks.wasCalled(path)).toBeFalsy();
+      var response = {};
+      $window.angular.callbacks._0(response);
+      expect($jsonpCallbacks.wasCalled(path)).toBeTruthy();
+    }));
+  });
+
+
+  describe('getResponse(callbackPath)', function() {
+
+    it('should retrieve the data from when the callback was called', inject(function($window, $jsonpCallbacks) {
+      var path = $jsonpCallbacks.createCallback('http://some.dummy.com/jsonp/request');
+      var response = {};
+      $window.angular.callbacks._0(response);
+      var result = $jsonpCallbacks.getResponse(path);
+      expect(result).toBe(response);
+    }));
+  });
+
+  describe('removeCallback(calbackPath)', function() {
+
+    it('should remove the callback', inject(function($window, $jsonpCallbacks) {
+      var path = $jsonpCallbacks.createCallback('http://some.dummy.com/jsonp/request');
+      $jsonpCallbacks.removeCallback(path);
+      expect($window.angular.callbacks._0).toBeUndefined();
+    }));
+  });
+});