Undo/Redo with Store History
Build a history stack around a writable store to support undo and redo.
Undo/Redo with Store History is a free Sveltejs Academy lesson on CoddyKit — lesson 4 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Sveltejs Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
History Stack
Wrap a writable store with past/present/future arrays to support undo/redo.
Basic Implementation
Maintain a list of previous states.
function createHistory(initial) {
let past = [], future = [];
const state = writable(initial);
return {
subscribe: state.subscribe,
set(v) { past.push(get(state)); future = []; state.set(v); },
undo() { if (past.length) { future.push(get(state)); state.set(past.pop()); } },
redo() { if (future.length) { past.push(get(state)); state.set(future.pop()); } }
};
}Limit Stack Size
Cap the history length to bound memory usage.
Deep Copies
Push deep copies of objects to avoid mutation issues.
Keyboard Shortcuts
Bind Ctrl+Z and Ctrl+Shift+Z to undo/redo for native feel.
Persisting History
Save to localStorage for cross-session undo (with care for size).
Performance
For large states, store diffs instead of full snapshots.
Branching
Most apps clear future on a new action; some editors keep a branching history.
Library Options
Libraries like svelte-undo provide ready-made history stores.
UI Hints
Disable undo/redo buttons when there is nothing to undo/redo.
Testing
Test sequences of actions + undo/redo to ensure correct rollback.
Quick Check
What does the future stack do?
Recap
Implement undo/redo with past/present/future stacks around a writable store. Cap size and bind shortcuts.
Frequently asked questions
Is the “Undo/Redo with Store History” lesson free?
Yes — the full text of “Undo/Redo with Store History” is free to read here on the web, and the Sveltejs Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Sveltejs Academy course, upgrade to CoddyKit PRO.
What will I learn in “Undo/Redo with Store History”?
Build a history stack around a writable store to support undo and redo. You practise Sveltejs Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Sveltejs Academy?
No prior experience is required. Sveltejs Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 4 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Undo/Redo with Store History” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Sveltejs Academy lesson?
Yes. Every Sveltejs Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Store Architecture: Feature Modules
- Event Bus Pattern with Stores
- Optimistic UI Updates
- Undo/Redo with Store History