From 9f7f80b5a8ff60df9e7e9a137703abade0fe69f2 Mon Sep 17 00:00:00 2001
From: Chris O <chris@prettycode.org>
Date: Wed, 17 Dec 2014 09:57:54 -0800
Subject: [PATCH 1/4] Simple non-breaking change to support deep extend.

---
 src/Angular.js      | 18 +++++++++++++++---
 test/AngularSpec.js | 12 ++++++++++++
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/src/Angular.js b/src/Angular.js
index 80a9eadb9795..2d61b44dcfb8 100644
--- a/src/Angular.js
+++ b/src/Angular.js
@@ -333,7 +333,7 @@ function setHashKey(obj, h) {
  * Extends the destination object `dst` by copying own enumerable properties from the `src` object(s)
  * to `dst`. You can specify multiple `src` objects. If you want to preserve original objects, you can do so
  * by passing an empty object as the target: `var object = angular.extend({}, object1, object2)`.
- * Note: Keep in mind that `angular.extend` does not support recursive merge (deep copy).
+ * Note: Pass `true` in as the last argument to perform a recursive merge (deep copy).
  *
  * @param {Object} dst Destination object.
  * @param {...Object} src Source object(s).
@@ -341,14 +341,26 @@ function setHashKey(obj, h) {
  */
 function extend(dst) {
   var h = dst.$$hashKey;
+  var argsLength = arguments.length;
+  var isDeep = (argsLength >= 3) && (arguments[argsLength - 1] === true);
 
-  for (var i = 1, ii = arguments.length; i < ii; i++) {
+  if (isDeep) {
+    delete arguments[argsLength - 1];
+  }
+
+  for (var i = 1; i < argsLength; i++) {
     var obj = arguments[i];
     if (obj) {
       var keys = Object.keys(obj);
       for (var j = 0, jj = keys.length; j < jj; j++) {
         var key = keys[j];
-        dst[key] = obj[key];
+        var src = obj[key];
+        
+        if (isDeep) { 
+          src = extend(dst[key], src, true);
+        }
+        
+        dst[key] = src;
       }
     }
   }
diff --git a/test/AngularSpec.js b/test/AngularSpec.js
index e63789100947..bc2e298b1aec 100644
--- a/test/AngularSpec.js
+++ b/test/AngularSpec.js
@@ -223,6 +223,18 @@ describe('angular', function() {
       // make sure we retain the old key
       expect(hashKey(dst)).toEqual(h);
     });
+
+    it('should perform deep extend when last argument is true', function() {
+      var src = { foo: { bar: 'foobar' }},
+          dst = { foo: { bazz: 'foobazz' }};
+      extend(dst, src, true);
+      expect(dst).toEqual({
+        foo: {
+          bar: 'foobar',
+          bazz: 'foobazz'
+        }
+      });
+    });
   });
 
   describe('shallow copy', function() {

From c291c5916b97944135fd00b3e1bbb86808ffc260 Mon Sep 17 00:00:00 2001
From: "Chris O." <chris@prettycode.org>
Date: Wed, 17 Dec 2014 15:02:35 -0800
Subject: [PATCH 2/4] Check property is object before deep-extending.

---
 src/Angular.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Angular.js b/src/Angular.js
index 2d61b44dcfb8..72281b259580 100644
--- a/src/Angular.js
+++ b/src/Angular.js
@@ -356,7 +356,7 @@ function extend(dst) {
         var key = keys[j];
         var src = obj[key];
         
-        if (isDeep) { 
+        if (isDeep && isObject(dst[key])) { 
           src = extend(dst[key], src, true);
         }
         

From d257ae0632477a107f3cc7b8e8b408d797d09bd6 Mon Sep 17 00:00:00 2001
From: "Chris O." <chris@prettycode.org>
Date: Wed, 17 Dec 2014 15:09:59 -0800
Subject: [PATCH 3/4] Updating test to be more thorough.

---
 test/AngularSpec.js | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/test/AngularSpec.js b/test/AngularSpec.js
index bc2e298b1aec..9cdf751d6efc 100644
--- a/test/AngularSpec.js
+++ b/test/AngularSpec.js
@@ -225,13 +225,16 @@ describe('angular', function() {
     });
 
     it('should perform deep extend when last argument is true', function() {
-      var src = { foo: { bar: 'foobar' }},
+      var src = { foo: { bar: 'foobar', age: 10, nothing: null, undef: void 0 }},
           dst = { foo: { bazz: 'foobazz' }};
       extend(dst, src, true);
       expect(dst).toEqual({
         foo: {
           bar: 'foobar',
-          bazz: 'foobazz'
+          bazz: 'foobazz',
+          age: 10,
+          nothing: null,
+          undef: void 0
         }
       });
     });

From e49ed06fd80eea9f1c6ac2206c5f143cd5c64dd2 Mon Sep 17 00:00:00 2001
From: "Chris O." <chris@prettycode.org>
Date: Wed, 17 Dec 2014 15:15:37 -0800
Subject: [PATCH 4/4] Removal of delete per user caitp.

---
 src/Angular.js | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/src/Angular.js b/src/Angular.js
index 72281b259580..cd95e8bf2ec0 100644
--- a/src/Angular.js
+++ b/src/Angular.js
@@ -344,9 +344,7 @@ function extend(dst) {
   var argsLength = arguments.length;
   var isDeep = (argsLength >= 3) && (arguments[argsLength - 1] === true);
 
-  if (isDeep) {
-    delete arguments[argsLength - 1];
-  }
+  if (isDeep) --argsLength;
 
   for (var i = 1; i < argsLength; i++) {
     var obj = arguments[i];