Add Visibility.notPrerender(callback) to run code not in prerender state

lib/visibility.js

@@ -40,6 +40,10 @@
         // visible.
         _onVisibleCallbacks: [],
 
+        // Callbacks from `notPrerender` method, that wait when visibility state
+        // change from “prerender”.
+        _notPrerenderCallbacks: [],
+
         // Last timer number.
         _lastTimer: 0,
 
@@ -118,6 +122,13 @@
                 this._onVisibleCallbacks = [];
             }
 
+            if ( 'prerender' != this.state() ) {
+                for ( var i = 0; i < this._notPrerenderCallbacks.length; i++ ) {
+                    this._notPrerenderCallbacks[i]();
+                }
+                this._notPrerenderCallbacks = [];
+            }
+
             this._hiddenBefore = isHidden;
         },
 
@@ -244,6 +255,19 @@
             this._setListener();
         },
 
+        // Call `callback` in any state, expect “prerender”. If current state
+        // is “prerender” it will wait until state will be changed.
+        // If Page Visibility API doesn’t supported, it will call `callback`
+        // immediately.
+        notPrerender: function (callback) {
+            if ( !this.support() || 'prerender' != this.state() ) {
+                callback();
+                return true;
+            }
+            this._notPrerenderCallbacks.push(callback);
+            this._setListener();
+        },
+
         // Run callback every `interval` milliseconds if page is visible and
         // every `hiddenInterval` milliseconds if page is hidden.
         //

spec/visibilitySpec.js

@@ -341,4 +341,49 @@ describe('Visibility', function () {
         expect( Visibility._runTimer.argsForCall[2] ).toEqual(['1', false]);
         expect( Visibility._runTimer.argsForCall[3] ).toEqual(['3', false]);
     });
+
+    it('should run notPrerender callback now without API support', function () {
+        spyOn(Visibility, 'support').andReturn(false);
+        spyOn(Visibility, '_setListener');
+        var callback = jasmine.createSpy();
+
+        Visibility.notPrerender(callback);
+
+        expect( callback ).toHaveBeenCalled();
+        expect( Visibility._setListener ).not.toHaveBeenCalled();
+    });
+
+    it('should run notPrerender now, if page isn’t prerended', function () {
+        Visibility._chechedPrefix = 'webkit';
+        document.webkitVisibilityState = 'hidden';
+        spyOn(Visibility, '_setListener');
+        var callback = jasmine.createSpy();
+
+        Visibility.notPrerender(callback);
+
+        expect( callback ).toHaveBeenCalled();
+        expect( Visibility._setListener ).not.toHaveBeenCalled();
+    });
+
+    it('should run notPrerender by listener on prerended page', function () {
+        Visibility._chechedPrefix = 'webkit';
+        document.webkitVisibilityState = 'prerender';
+        spyOn(Visibility, '_setListener');
+        var callback = jasmine.createSpy();
+
+        Visibility.notPrerender(callback);
+
+        expect( callback ).not.toHaveBeenCalled();
+        expect( Visibility._setListener ).toHaveBeenCalled();
+
+        Visibility._onVisibilityChange();
+        expect( callback ).not.toHaveBeenCalled();
+
+        document.webkitVisibilityState = 'visible';
+        Visibility._onVisibilityChange();
+        expect( callback ).toHaveBeenCalled();
+
+        Visibility._onVisibilityChange();
+        expect( callback.callCount ).toEqual(1);
+    });
 });