Draggable: make sure snap elements are in the document before snappin…

…g. Fixes #8459 - Draggable: element can snap to an element that was removed during drag.(cherry picked from commit 9d8af80)

tests/unit/draggable/draggable_options.js

@@ -1257,6 +1257,39 @@ test( "snap, snapMode, and snapTolerance", function() {
 	deepEqual( element.offset(), { top: newY, left: newX }, "doesn't snap on the inner snapTolerance area when snapMode is outer" );
 });
 
+test( "#8459: element can snap to an element that was removed during drag", function() {
+	expect( 1 );
+
+	var newX, newY,
+		snapTolerance = 15,
+		element = $( "#draggable1" ).draggable({
+			snap: true,
+			snapMode: "both",
+			snapTolerance: snapTolerance,
+			start: function() {
+				element2.remove();
+			}
+		}),
+		element2 = $( "#draggable2" ).draggable();
+
+	element.offset({
+		top: 1,
+		left: 1
+	});
+
+	newX = element2.offset().left - element.outerWidth() - snapTolerance + 1;
+	newY = element2.offset().top;
+
+	element.simulate( "drag", {
+		handle: "corner",
+		x: newX,
+		y: newY,
+		moves: 1
+	});
+
+	deepEqual( element.offset(), { top: newY, left: newX }, "doesn't snap to a removed element" );
+});
+
 test( "#8165: Snapping large rectangles to small rectangles doesn't snap properly", function() {
 	expect( 1 );
 

ui/jquery.ui.draggable.js

@@ -217,9 +217,7 @@ $.widget("ui.draggable", $.ui.mouse, {
 	_mouseStop: function(event) {
 
 		//If we are using droppables, inform the manager about the drop
-		var element,
-			that = this,
-			elementInDom = false,
+		var that = this,
 			dropped = false;
 		if ($.ui.ddmanager && !this.options.dropBehaviour) {
 			dropped = $.ui.ddmanager.drop(this, event);
@@ -232,13 +230,7 @@ $.widget("ui.draggable", $.ui.mouse, {
 		}
 
 		//if the original element is no longer in the DOM don't bother to continue (see #8269)
-		element = this.element[0];
-		while ( element && (element = element.parentNode) ) {
-			if (element === document ) {
-				elementInDom = true;
-			}
-		}
-		if ( !elementInDom && this.options.helper === "original" ) {
+		if ( this.options.helper === "original" && !$.contains( this.element[ 0 ].ownerDocument, this.element[ 0 ] ) ) {
 			return false;
 		}
 
@@ -850,7 +842,7 @@ $.ui.plugin.add("draggable", "snap", {
 			t = inst.snapElements[i].top;
 			b = t + inst.snapElements[i].height;
 
-			if(x2 < l - d || x1 > r + d || y2 < t - d || y1 > b + d) {
+			if ( x2 < l - d || x1 > r + d || y2 < t - d || y1 > b + d || !$.contains( inst.snapElements[ i ].item.ownerDocument, inst.snapElements[ i ].item ) ) {
 				if(inst.snapElements[i].snapping) {
 					(inst.options.snap.release && inst.options.snap.release.call(inst.element, event, $.extend(inst._uiHash(), { snapItem: inst.snapElements[i].item })));
 				}