mirror of
https://github.com/kjanat/livedash-node.git
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Kaj Kowalski
cd05fc8648
- Fix syntax errors in skills markdown files (.github/skills, .opencode/skills) - Change typescript to tsx for code blocks with JSX - Replace ellipsis (...) in array examples with valid syntax - Separate CSS from TypeScript into distinct code blocks - Convert JavaScript object examples to valid JSON in docs - Fix enum definitions with proper comma separation
100 lines
2.5 KiB
Markdown
100 lines
2.5 KiB
Markdown
---
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title: Strategic Suspense Boundaries
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impact: HIGH
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impactDescription: faster initial paint
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tags: async, suspense, streaming, layout-shift
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---
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## Strategic Suspense Boundaries
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Instead of awaiting data in async components before returning JSX, use Suspense boundaries to show the wrapper UI faster while data loads.
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**Incorrect (wrapper blocked by data fetching):**
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```tsx
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async function Page() {
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const data = await fetchData(); // Blocks entire page
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return (
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<div>
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<div>Sidebar</div>
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<div>Header</div>
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<div>
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<DataDisplay data={data} />
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</div>
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<div>Footer</div>
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</div>
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);
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}
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```
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The entire layout waits for data even though only the middle section needs it.
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**Correct (wrapper shows immediately, data streams in):**
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```tsx
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function Page() {
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return (
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<div>
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<div>Sidebar</div>
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<div>Header</div>
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<div>
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<Suspense fallback={<Skeleton />}>
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<DataDisplay />
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</Suspense>
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</div>
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<div>Footer</div>
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</div>
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);
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}
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async function DataDisplay() {
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const data = await fetchData(); // Only blocks this component
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return <div>{data.content}</div>;
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}
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```
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Sidebar, Header, and Footer render immediately. Only DataDisplay waits for data.
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**Alternative (share promise across components):**
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```tsx
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function Page() {
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// Start fetch immediately, but don't await
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const dataPromise = fetchData();
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return (
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<div>
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<div>Sidebar</div>
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<div>Header</div>
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<Suspense fallback={<Skeleton />}>
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<DataDisplay dataPromise={dataPromise} />
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<DataSummary dataPromise={dataPromise} />
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</Suspense>
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<div>Footer</div>
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</div>
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);
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}
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function DataDisplay({ dataPromise }: { dataPromise: Promise<Data> }) {
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const data = use(dataPromise); // Unwraps the promise
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return <div>{data.content}</div>;
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}
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function DataSummary({ dataPromise }: { dataPromise: Promise<Data> }) {
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const data = use(dataPromise); // Reuses the same promise
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return <div>{data.summary}</div>;
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}
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```
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Both components share the same promise, so only one fetch occurs. Layout renders immediately while both components wait together.
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**When NOT to use this pattern:**
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- Critical data needed for layout decisions (affects positioning)
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- SEO-critical content above the fold
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- Small, fast queries where suspense overhead isn't worth it
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- When you want to avoid layout shift (loading → content jump)
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**Trade-off:** Faster initial paint vs potential layout shift. Choose based on your UX priorities.
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