Fix #12120. Always stack .before/.after, and fix disconnected nodes.

src/manipulation.js

@@ -148,10 +148,7 @@ jQuery.fn.extend({
 			});
 		}
 
-		if ( arguments.length ) {
-			var set = jQuery.clean( arguments );
-			return this.pushStack( jQuery.merge( set, this ), "before", this.selector );
-		}
+		return this.pushStack( jQuery.merge( jQuery.clean( arguments ), this ), "before", this.selector );
 	},
 
 	after: function() {
@@ -161,10 +158,7 @@ jQuery.fn.extend({
 			});
 		}
 
-		if ( arguments.length ) {
-			var set = jQuery.clean( arguments );
-			return this.pushStack( jQuery.merge( this, set ), "after", this.selector );
-		}
+		return this.pushStack( jQuery.merge( this.toArray(), jQuery.clean( arguments ) ), "after", this.selector );
 	},
 
 	// keepData is for internal use only--do not document
@@ -721,6 +715,7 @@ jQuery.extend({
 
 		// Fix #11356: Clear elements from safeFragment
 		if ( div ) {
+			div.innerHTML = "";
 			safe.removeChild( div );
 			elem = div = safe = null;
 		}

test/unit/manipulation.js

@@ -909,12 +909,13 @@ test("before(Function)", function() {
 	testBefore(manipulationFunctionReturningObj);
 });
 
-test("before and after w/ empty object (#10812)", function() {
-	expect(2);
+test("before and after w/ empty object (#10812, #12120)", function() {
+	expect(3);
 
-	var res = jQuery( "#notInTheDocument" ).before( "(" ).after( ")" );
-	equal( res.length, 2, "didn't choke on empty object" );
-	equal( res.wrapAll("<div/>").parent().text(), "()", "correctly appended text" );
+	var res = jQuery("#notInTheDocument").before("<span>(</span>").after("<span>)</span>");
+	equal( res.length, 2, "added two elements to the empty object" );
+	equal( res.text(), "()", "correctly appended text" );
+	equal( res.end().text(), "(", "stacked the previous value" );
 });
 
 test("before and after on disconnected node (#10517)", function() {