Created a flag called $skipChildWatchers that has the depth-first traversal of the digest loop skip a scope's children when that flag is true.

Author: vahan-hartooni

src/ng/rootScope.js

@@ -136,6 +136,7 @@ function $RootScopeProvider() {
       this.$$listeners = {};
       this.$$listenerCount = {};
       this.$$isolateBindings = null;
+      this.$skipChildWatchers = false;
     }
 
     /**
@@ -162,6 +163,14 @@ function $RootScopeProvider() {
        * Reference to the root scope.
        */
 
+      /**
+       * @ngdoc property
+       * @name $rootScope.Scope#$skipChildWatchers
+       *
+       * @description
+       * If set to true, $digest loop bypasses this scope's children
+       */
+
     Scope.prototype = {
       constructor: Scope,
       /**
@@ -794,7 +803,7 @@ function $RootScopeProvider() {
             // Insanity Warning: scope depth-first traversal
             // yes, this code is a bit crazy, but it works and we have tests to prove it!
             // this piece should be kept in sync with the traversal in $broadcast
-            if (!(next = (current.$$childHead ||
+            if (!(next = ((!current.$skipChildWatchers && current.$$childHead) ||
                 (current !== target && current.$$nextSibling)))) {
               while (current !== target && !(next = current.$$nextSibling)) {
                 current = current.$parent;

test/ng/rootScopeSpec.js

@@ -49,6 +49,12 @@ describe('Scope', function() {
     }));
   });
 
+  describe('$skipChildWatchers', function() {
+    it('should initially be false', inject(function($rootScope) {
+      expect($rootScope.$skipChildWatchers).toBeDefined();
+      expect($rootScope.$skipChildWatchers).toEqual(false);
+    }));
+  });
 
   describe('this', function() {
     it('should evaluate \'this\' to be the scope', inject(function($rootScope) {
@@ -458,6 +464,59 @@ describe('Scope', function() {
       expect(log).toEqual([]);
     }));
 
+    it('should $digest scope marked $skipChildWatchers to true, but not its children.',
+        inject(function ($rootScope) {
+      var log = '',
+          parent = $rootScope.$new(),
+          childA = parent.$new(),
+          childB = parent.$new();
+
+      parent.$watch(function(){ log += 'a';});
+      childA.$watch(function(){ log += 'b';});
+      childB.$watch(function(){ log += 'c';});
+      parent.$skipChildWatchers = true;
+
+      $rootScope.$digest();
+      expect(log).toEqual('aa');
+    }));
+
+    it('should $digest children after parent\'s $skipChildWatchers is set back to false',
+      inject(function ($rootScope) {
+        var log = '',
+          parent = $rootScope.$new(),
+          childA = parent.$new(),
+          childB = parent.$new();
+
+        parent.$watch(function(){ log+='a'});
+        childA.$watch('a', function(v){
+            $rootScope.b = v;
+            log += 'b'
+        });
+        childB.$watch('b', function(v){
+            $rootScope.c = v;
+            log += 'c'
+        });
+
+        $rootScope.$digest();
+        expect(log).toEqual('abca');
+
+        log = '';
+        parent.a = 1;
+        parent.$skipChildWatchers = true;
+
+        $rootScope.$digest();
+        expect(log).toEqual('a');
+        expect($rootScope.b).toBeUndefined();
+        expect($rootScope.c).toBeUndefined();
+
+        log = '';
+        parent.$skipChildWatchers = false;
+
+        $rootScope.$digest();
+        expect(log).toEqual('abca');
+        expect($rootScope.b).toEqual(1);
+        expect($rootScope.c).toEqual(1);
+      }));
 
     describe('$watch deregistration', function() {