API Reference > imodeljs-markup > MarkupTools > UndoManager > performOperation performOperation Method Perform a series of changes to markup elements that should all be reversed as a single operation. performOperation(cmdName: string, fn: VoidFunction): void note all of the onXXX methods of this class should only be called from within the callback function of this method. Parameter Type Description cmdName string fn VoidFunction the function that performs the changes to the elements. It must call the onXXX methods of this class to storethe operations in the undo buffer. Returns - void Defined in core/markup/src/Undo.ts Line 109 Last Updated: 13 June, 2024