API Reference > imodeljs-markup > MarkupTools > UndoManager UndoManager Class Stores the sequence of operations performed on a Markup. Facilitates undo/redo of the operations. Methods Name Description constructor(): UndoManager doRedo(): void reinstate the most recently reversed operation, if any doUndo(): void reverse the most recent operation, if any onAdded(elem: Element): void call this from within a UndoManager.performOperation function after an element has been added to a markup onDelete(elem: Element): void call this from within a UndoManager.performOperation function before an element is about to be deleted from a markup onModified(newElem: Element, oldElem: Element): void call this from within a UndoManager.performOperation function after an element has been modified in a markup onRepositioned(elem: Element, oldIndex: number, oldParent: Element): void call this from within a UndoManager.performOperation function after an element has been moved in display order in a markup performOperation(cmdName: string, fn: VoidFunction): void Perform a series of changes to markup elements that should all be reversed as a single operation. Properties Name Type Description redoPossible Accessor ReadOnly boolean determine whether there are any reversed operations redoString Accessor ReadOnly undefined | string the name of the operation that can be redone (or undefined) undoPossible Accessor ReadOnly boolean determine whether there are any un-reversed operations undoString Accessor ReadOnly undefined | string the name of the operation that can be undone (or undefined) Defined in markup/src/Undo.ts Line 86 Last Updated: 11 June, 2024