38 lines
966 B
Markdown
38 lines
966 B
Markdown
---
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title: Conditional Module Loading
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impact: HIGH
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impactDescription: loads large data only when needed
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tags: bundle, conditional-loading, lazy-loading
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---
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## Conditional Module Loading
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Load large data or modules only when a feature is activated.
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**Example (lazy-load animation frames):**
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```tsx
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function AnimationPlayer({
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enabled,
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setEnabled,
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}: {
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enabled: boolean;
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setEnabled: React.Dispatch<React.SetStateAction<boolean>>;
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}) {
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const [frames, setFrames] = useState<Frame[] | null>(null);
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useEffect(() => {
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if (enabled && !frames && typeof window !== "undefined") {
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import("./animation-frames.js")
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.then((mod) => setFrames(mod.frames))
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.catch(() => setEnabled(false));
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}
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}, [enabled, frames, setEnabled]);
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if (!frames) return <Skeleton />;
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return <Canvas frames={frames} />;
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}
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```
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The `typeof window !== 'undefined'` check prevents bundling this module for SSR, optimizing server bundle size and build speed.
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