Ref #13019 and gh-1062. Use parentNode check instead of isDisconnected().

src/manipulation.js

@@ -141,7 +141,7 @@ jQuery.fn.extend({
 
 	before: function() {
 		return this.domManip( arguments, false, function( elem ) {
-			if ( !isDisconnected( this ) ) {
+			if ( this.parentNode ) {
 				this.parentNode.insertBefore( elem, this );
 			}
 		});
@@ -149,7 +149,7 @@ jQuery.fn.extend({
 
 	after: function() {
 		return this.domManip( arguments, false, function( elem ) {
-			if ( !isDisconnected( this ) ) {
+			if ( this.parentNode ) {
 				this.parentNode.insertBefore( elem, this.nextSibling );
 			}
 		});
@@ -258,12 +258,11 @@ jQuery.fn.extend({
 		}
 
 		return this.domManip( [ value ], true, function( elem ) {
-			var next, parent;
-
-			if ( !isDisconnected( this ) && this.nodeType === 1 || this.nodeType === 11 ) {
-				next = this.nextSibling;
+			var next = this.nextSibling,
 				parent = this.parentNode;
 
+			if ( parent && this.nodeType === 1 || this.nodeType === 11 ) {
+
 				jQuery( this ).remove();
 
 				if ( next ) {

src/traversing.js

@@ -131,12 +131,6 @@ jQuery.fn.extend({
 
 jQuery.fn.andSelf = jQuery.fn.addBack;
 
-// A painfully simple check to see if an element is disconnected
-// from a document (should be improved, where feasible).
-function isDisconnected( node ) {
-	return !node || !node.parentNode || node.parentNode.nodeType === 11;
-}
-
 function sibling( cur, dir ) {
 	do {
 		cur = cur[ dir ];