feat($browser): JSONP error handling

since we don't know if the error was due to a client error (4xx) or
server error (5xx), we leave the status code as undefined.

src/Browser.js

@@ -100,12 +100,19 @@ function Browser(window, document, body, XHR, $log) {
     outstandingRequestCount ++;
     if (lowercase(method) == 'json') {
       var callbackId = ("angular_" + Math.random() + '_' + (idCounter++)).replace(/\d\./, '');
-      var script = self.addJs(url.replace('JSON_CALLBACK', callbackId));
+      window[callbackId] = function(data) {
-      window[callbackId] = function(data){
+        window[callbackId].data = data;
+      };
+
+      var script = self.addJs(url.replace('JSON_CALLBACK', callbackId), null, function() {
+        if (window[callbackId].data) {
+          completeOutstandingRequest(callback, 200, window[callbackId].data);
+        } else {
+          completeOutstandingRequest(callback);
+        }
         delete window[callbackId];
         body[0].removeChild(script);
-        completeOutstandingRequest(callback, 200, data);
+      });
-      };
     } else {
       var xhr = new XHR();
       xhr.open(method, url, true);
@@ -452,7 +459,7 @@ function Browser(window, document, body, XHR, $log) {
    * @description
    * Adds a script tag to the head.
    */
-  self.addJs = function(url, domId) {
+  self.addJs = function(url, domId, done) {
     // we can't use jQuery/jqLite here because jQuery does crazy shit with script elements, e.g.:
     // - fetches local scripts via XHR and evals them
     // - adds and immediately removes script elements from the document
@@ -465,6 +472,15 @@ function Browser(window, document, body, XHR, $log) {
     script.type = 'text/javascript';
     script.src = url;
     if (domId) script.id = domId;
+
+    if (msie) {
+      script.onreadystatechange = function() {
+        /loaded|complete/.test(script.readyState) && done && done();
+      }
+    } else {
+      if (done) script.onload = script.onerror = done;
+    }
+
     body[0].appendChild(script);
 
     return script;

test/BrowserSpecs.js

@@ -87,27 +87,81 @@ describe('browser', function(){
 
   describe('xhr', function(){
     describe('JSON', function(){
-      it('should add script tag for request', function() {
+      var log;
-        var callback = jasmine.createSpy('callback');
+
-        var log = "";
+      function callback(code, data) {
-        browser.xhr('JSON', 'http://example.org/path?cb=JSON_CALLBACK', null, function(code, data){
+        log += code + ':' + data + ';';
-          log += code + ':' + data + ';';
+      }
-        });
+
-        browser.notifyWhenNoOutstandingRequests(callback);
+      beforeEach(function() {
-        expect(callback).not.toHaveBeenCalled();
+        log = "";
-        expect(scripts.length).toEqual(1);
-        var script = scripts[0];
-        var url = script.src.split('?cb=');
-        expect(url[0]).toEqual('http://example.org/path');
-        expect(typeof fakeWindow[url[1]]).toEqual($function);
-        fakeWindow[url[1]]('data');
-        expect(callback).toHaveBeenCalled();
-        expect(log).toEqual('200:data;');
-        expect(scripts).toEqual(removedScripts);
-        expect(fakeWindow[url[1]]).toBeUndefined();
       });
+
+
+      // We don't have unit tests for IE because script.readyState is readOnly.
+      // Instead we run e2e tests on all browsers - see e2e for $xhr.
+      if (!msie) {
+
+        it('should add script tag for JSONP request', function() {
+          var notify = jasmine.createSpy('notify');
+          browser.xhr('JSON', 'http://example.org/path?cb=JSON_CALLBACK', null, callback);
+          browser.notifyWhenNoOutstandingRequests(notify);
+          expect(notify).not.toHaveBeenCalled();
+          expect(scripts.length).toEqual(1);
+          var script = scripts[0];
+          var url = script.src.split('?cb=');
+          expect(url[0]).toEqual('http://example.org/path');
+          expect(typeof fakeWindow[url[1]]).toEqual($function);
+          fakeWindow[url[1]]('data');
+          script.onload();
+
+          expect(notify).toHaveBeenCalled();
+          expect(log).toEqual('200:data;');
+          expect(scripts).toEqual(removedScripts);
+          expect(fakeWindow[url[1]]).toBeUndefined();
+        });
+
+
+        it('should call callback when script fails to load', function() {
+          browser.xhr('JSON', 'http://example.org/path?cb=JSON_CALLBACK', null, callback);
+          var script = scripts[0];
+          expect(typeof script.onload).toBe($function);
+          expect(typeof script.onerror).toBe($function);
+          script.onerror();
+
+          expect(log).toEqual('undefined:undefined;');
+        });
+
+
+        it('should update the outstandingRequests counter for successful requests', function() {
+          var notify = jasmine.createSpy('notify');
+          browser.xhr('JSON', 'http://example.org/path?cb=JSON_CALLBACK', null, callback);
+          browser.notifyWhenNoOutstandingRequests(notify);
+          expect(notify).not.toHaveBeenCalled();
+
+          var script = scripts[0];
+          var url = script.src.split('?cb=');
+          fakeWindow[url[1]]('data');
+          script.onload();
+
+          expect(notify).toHaveBeenCalled();
+        });
+
+
+        it('should update the outstandingRequests counter for failed requests', function() {
+          var notify = jasmine.createSpy('notify');
+          browser.xhr('JSON', 'http://example.org/path?cb=JSON_CALLBACK', null, callback);
+          browser.notifyWhenNoOutstandingRequests(notify);
+          expect(notify).not.toHaveBeenCalled();
+
+          scripts[0].onerror();
+
+          expect(notify).toHaveBeenCalled();
+        });
+      }
     });
 
+
     it('should normalize IE\'s 1223 status code into 204', function() {
       var callback = jasmine.createSpy('XHR');