Developer Implements Command Pattern in JavaScript with Undo Functionality

A developer completed a JavaScript design patterns exercise by building a simple text editor using the Command Pattern. The implementation encapsulates editing actions — such as appending and deleting text — as discrete command objects, making them easier to execute and reverse. Four core components were used: a TextEditor receiver, AppendCommand and DeleteCommand classes, and an EditorInvoker that maintains a history stack. The invoker executes commands and enables undo operations by popping the most recent command from history and calling its undo method. Tests were written using Node.js's built-in assert module to verify the behavior of each component.