Unify the means of detecting a window across the library. Fixes jQuer…

…y UI bug #5438 and jQuery bugs #6575 and 6088.

src/core.js

@@ -474,6 +474,11 @@ jQuery.extend({
 		return jQuery.type(obj) === "array";
 	},
 
+	// A crude way of determining if an object is a window
+	isWindow: function( obj ) {
+		return "setInterval" in obj;
+	},
+
 	type: function( obj ) {
 		return obj == null ?
 			String( obj ) :
@@ -484,7 +489,7 @@ jQuery.extend({
 		// Must be an Object.
 		// Because of IE, we also have to check the presence of the constructor property.
 		// Make sure that DOM nodes and window objects don't pass through, as well
-		if ( !obj || jQuery.type(obj) !== "object" || obj.nodeType || obj.setInterval ) {
+		if ( !obj || jQuery.type(obj) !== "object" || obj.nodeType || jQuery.isWindow( obj ) ) {
 			return false;
 		}
 
@@ -632,7 +637,7 @@ jQuery.extend({
 			// Tweaked logic slightly to handle Blackberry 4.7 RegExp issues #6930
 			var type = jQuery.type(array);
 
-			if ( array.length == null || type === "string" || type === "function" || type === "regexp" || "setInterval" in array ) {
+			if ( array.length == null || type === "string" || type === "function" || type === "regexp" || jQuery.isWindow( array ) ) {
 				push.call( ret, array );
 			} else {
 				jQuery.merge( ret, array );

src/dimensions.js

@@ -33,7 +33,7 @@ jQuery.each([ "Height", "Width" ], function( i, name ) {
 			});
 		}
 
-		return ("scrollTo" in elem && elem.document) ? // does it walk and quack like a window?
+		return jQuery.isWindow( elem ) ?
 			// Everyone else use document.documentElement or document.body depending on Quirks vs Standards mode
 			elem.document.compatMode === "CSS1Compat" && elem.document.documentElement[ "client" + name ] ||
 			elem.document.body[ "client" + name ] :

src/event.js

@@ -25,7 +25,7 @@ jQuery.event = {
 
 		// For whatever reason, IE has trouble passing the window object
 		// around, causing it to be cloned in the process
-		if ( elem.setInterval && ( elem !== window && !elem.frameElement ) ) {
+		if ( jQuery.isWindow( elem ) && ( elem !== window && !elem.frameElement ) ) {
 			elem = window;
 		}
 
@@ -515,7 +515,7 @@ jQuery.event = {
 		beforeunload: {
 			setup: function( data, namespaces, eventHandle ) {
 				// We only want to do this special case on windows
-				if ( this.setInterval ) {
+				if ( jQuery.isWindow( this ) ) {
 					this.onbeforeunload = eventHandle;
 				}
 			},

src/offset.js

@@ -280,7 +280,7 @@ jQuery.each( ["Left", "Top"], function( i, name ) {
 });
 
 function getWindow( elem ) {
-	return ("scrollTo" in elem && elem.document) ?
+	return jQuery.isWindow( elem ) ?
 		elem :
 		elem.nodeType === 9 ?
 			elem.defaultView || elem.parentWindow :