Fix exceptions on sub-objects (reformat pull request from @Robinfr). Closes cdinger#2.

Author: cdinger

jquery.objectdiff.js

@@ -30,6 +30,8 @@
             c[prop] = $.objectDiff(a[prop], b[prop], c);
           }
           else {
+            if(a === undefined) a = {};
+            if(b === undefined) b = {};
             if (a[prop] !== b[prop]) {
               c[prop] = [a[prop], b[prop]];
             }

spec/objectdiff_spec.js

@@ -34,5 +34,12 @@ describe("objectDiff", function() {
     var diff = {};
     expect($.objectDiff(before, after)).toEqual(diff);
   });
-});
 
+  // Github issue #2
+  it("should not throw exception when encountering sub-objects", function() {
+    var a = { x: { i:1, j:2, k: 3 }};
+    var b = { x: { i:2, j:2, k: 3 }, y: { i:2 }};
+    var diff = {x:{i:[1,2]}, y:{i:[undefined,2]}};
+    expect($.objectDiff(a, b)).toEqual(diff);
+  });
+});