| 1 | --- |
| 2 | title: Conditional Module Loading |
| 3 | impact: HIGH |
| 4 | impactDescription: loads large data only when needed |
| 5 | tags: bundle, conditional-loading, lazy-loading |
| 6 | --- |
| 7 | |
| 8 | ## Conditional Module Loading |
| 9 | |
| 10 | Load large data or modules only when a feature is activated. |
| 11 | |
| 12 | **Example (lazy-load animation frames):** |
| 13 | |
| 14 | ```tsx |
| 15 | function AnimationPlayer({ enabled, setEnabled }: { enabled: boolean; setEnabled: React.Dispatch<React.SetStateAction<boolean>> }) { |
| 16 | const [frames, setFrames] = useState<Frame[] | null>(null) |
| 17 | |
| 18 | useEffect(() => { |
| 19 | if (enabled && !frames && typeof window !== 'undefined') { |
| 20 | import('./animation-frames.js') |
| 21 | .then(mod => setFrames(mod.frames)) |
| 22 | .catch(() => setEnabled(false)) |
| 23 | } |
| 24 | }, [enabled, frames, setEnabled]) |
| 25 | |
| 26 | if (!frames) return <Skeleton /> |
| 27 | return <Canvas frames={frames} /> |
| 28 | } |
| 29 | ``` |
| 30 | |
| 31 | The `typeof window !== 'undefined'` check prevents bundling this module for SSR, optimizing server bundle size and build speed. |
| 32 |