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. This is 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, and your progress syncs across the web and the CoddyKit app. The Sveltejs Academy course includes 4 lessons in total.
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.
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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. 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. The Sveltejs Academy course includes 4 lessons in total.
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, so you can start here or from the beginning and move at your own pace. This is lesson 4 of 4.
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