add doc parameter to UndoManager

src/utils/UndoManager.js

@@ -139,6 +139,7 @@ const popStackItem = (undoManager, stack, eventType) => {
  * undo/redo scope.
  * @property {Set<any>} [UndoManagerOptions.trackedOrigins=new Set([null])]
  * @property {boolean} [ignoreRemoteMapChanges] Experimental. By default, the UndoManager will never overwrite remote changes. Enable this property to enable overwriting remote changes on key-value changes (Y.Map, properties on Y.Xml, etc..).
+ * @property {Doc} [doc] The document that this UndoManager operates on. Only needed if typeScope is empty.
  */
 
 /**
@@ -160,7 +161,8 @@ export class UndoManager extends Observable {
     captureTransaction = tr => true,
     deleteFilter = () => true,
     trackedOrigins = new Set([null]),
-    ignoreRemoteMapChanges = false
+    ignoreRemoteMapChanges = false,
+    doc = /** @type {Doc} */ (array.isArray(typeScope) ? typeScope[0].doc : typeScope.doc)
   } = {}) {
     super()
     /**
@@ -187,7 +189,7 @@ export class UndoManager extends Observable {
      */
     this.undoing = false
     this.redoing = false
-    this.doc = /** @type {Doc} */ (this.scope[0].doc)
+    this.doc = doc
     this.lastChange = 0
     this.ignoreRemoteMapChanges = ignoreRemoteMapChanges
     /**

tests/undo-redo.tests.js

@@ -49,6 +49,20 @@ export const testUndoText = tc => {
   t.compare(text0.toDelta(), [{ insert: 'b' }, { insert: 'cxy', attributes: { bold: true } }, { insert: 'z' }])
 }
 
+/**
+ * Test case to fix #241
+ * @param {t.TestCase} tc
+ */
+export const testEmptyTypeScope = tc => {
+  const ydoc = new Y.Doc()
+  const um = new Y.UndoManager([], { doc: ydoc })
+  const yarray = ydoc.getArray()
+  um.addToScope(yarray)
+  yarray.insert(0, [1])
+  um.undo()
+  t.assert(yarray.length === 0)
+}
+
 /**
  * Test case to fix #241
  * @param {t.TestCase} tc