Writing a tiny undo/redo stack in JavaScript

UI Algorithms: A Tiny Undo Stack I’ve needed this before - a couple of times. Third time I figured I needed something small, nimble - yet complete. And - at the same time - wondering about how to do it in a very simple manner. I think it worked out great, so let’s dig in. Undo histories and managers Most UIs will have some form of undo functionality. Now, there are generally two forms of it: undo stacks and version histories. A “version history” is what Photoshop history gives you - the ability to “paint through” to a previous state of the system. You can add five paint strokes, and then reveal a stroke you have made 4 steps back. But most apps won’t need that. What you will need is an undo stack, which can be specced out as follows: An undoable action gets performed and gets pushed onto the stack. If undo is requested, the stack is popped and the rollback action gets applied for the popped action. If an action was undone, you can redo that action. If you have undone 2 actions, ... Read full article.