DragEvent handling, null check fixes

Author: dbseel

src/record/mutation.ts

@@ -270,7 +270,10 @@ export default class MutationBuffer {
       const shadowHost: Element | null = n.getRootNode
         ? (n.getRootNode() as ShadowRoot)?.host
         : null;
-      const notInDoc = !this.doc.contains(n) && !this.doc.contains(shadowHost);
+      // ensure shadowHost is a Node, or doc.contains will throw an error
+      const notInDoc =
+        !this.doc.contains(n) &&
+        (!(shadowHost instanceof Node) || !this.doc.contains(shadowHost));
       if (!n.parentNode || notInDoc) {
         return;
       }
@@ -358,13 +361,16 @@ export default class MutationBuffer {
       if (!node) {
         for (let index = addList.length - 1; index >= 0; index--) {
           const _node = addList.get(index)!;
-          const parentId = this.mirror.getId(
-            (_node.value.parentNode as Node) as INode,
-          );
-          const nextId = getNextId(_node.value);
-          if (parentId !== -1 && nextId !== -1) {
-            node = _node;
-            break;
+          // ensure _node is defined before attempting to find value
+          if (_node) {
+            const parentId = this.mirror.getId(
+              (_node.value.parentNode as Node) as INode,
+            );
+            const nextId = getNextId(_node.value);
+            if (parentId !== -1 && nextId !== -1) {
+              node = _node;
+              break;
+            }
           }
         }
       }

src/record/observer.ts

@@ -194,21 +194,43 @@ function initMoveObserver(
     },
     callbackThreshold,
   );
-  const updatePosition = throttle<MouseEvent | TouchEvent | DragEvent>(
+
+  // update position for mouse, touch, and drag events (drag event extends mouse event)
+  function handleUpdatePositionEvent(evt: MouseEvent | TouchEvent) {
+    const target = getEventTarget(evt);
+    const { clientX, clientY } = isTouchEvent(evt)
+      ? evt.changedTouches[0]
+      : evt;
+    if (!timeBaseline) {
+      timeBaseline = Date.now();
+    }
+    positions.push({
+      x: clientX,
+      y: clientY,
+      id: mirror.getId(target as INode),
+      timeOffset: Date.now() - timeBaseline,
+    });
+  }
+
+  // separate call for non-drag events, in case DragEvent is not defined
+  const updatePosition = throttle<MouseEvent | TouchEvent>(
     (evt) => {
-      const target = getEventTarget(evt);
-      const { clientX, clientY } = isTouchEvent(evt)
-        ? evt.changedTouches[0]
-        : evt;
-      if (!timeBaseline) {
-        timeBaseline = Date.now();
-      }
-      positions.push({
-        x: clientX,
-        y: clientY,
-        id: mirror.getId(target as INode),
-        timeOffset: Date.now() - timeBaseline,
-      });
+      handleUpdatePositionEvent(evt);
+      wrappedCb(
+        evt instanceof MouseEvent
+          ? IncrementalSource.MouseMove
+          : IncrementalSource.TouchMove,
+      );
+    },
+    threshold,
+    {
+      trailing: false,
+    },
+  );
+  // call for drag events, when DragEvent is defined
+  const updateDragPosition = throttle<MouseEvent | TouchEvent | DragEvent>(
+    (evt) => {
+      handleUpdatePositionEvent(evt);
       wrappedCb(
         evt instanceof DragEvent
           ? IncrementalSource.Drag
@@ -222,10 +244,13 @@ function initMoveObserver(
       trailing: false,
     },
   );
+  // it is possible DragEvent is undefined even on devices
+  // that support event 'drag'
+  const dragEventDefined = typeof DragEvent !== 'undefined';
   const handlers = [
     on('mousemove', updatePosition, doc),
     on('touchmove', updatePosition, doc),
-    on('drag', updatePosition, doc),
+    on('drag', dragEventDefined ? updateDragPosition : updatePosition, doc),
   ];
   return () => {
     handlers.forEach((h) => h());