---
name: solid-core-rendering
description: "SolidJS rendering: render for client apps, hydrate for SSR, renderToString for server rendering, renderToStream for streaming, isServer checks."
metadata:
globs:
- "**/entry-*.tsx"
- "**/*render*"
---
# SolidJS Rendering Utilities
Complete guide to rendering SolidJS applications. Understand client-side rendering, SSR, hydration, and streaming.
## render - Client-Side Rendering
Mount your Solid app to the DOM. Essential browser entry point for SPAs.
```tsx
import { render } from "solid-js/web";
const dispose = render(() => , document.getElementById("app")!);
// Later, unmount
dispose();
```
**Key points:**
- First argument must be a **function** (not JSX directly)
- Element should be empty (render appends, dispose removes all)
- Returns dispose function to unmount
**Correct usage:**
```tsx
// ✅ Correct - function
render(() => , element);
// ❌ Wrong - JSX directly
render(, element);
```
## hydrate - SSR Hydration
Hydrate server-rendered HTML with client-side code. Essential for SSR apps.
```tsx
import { hydrate } from "solid-js/web";
const dispose = hydrate(() => , document.getElementById("app")!);
```
**Key points:**
- Rehydrates existing DOM
- Matches server-rendered structure
- Attaches interactivity
- Used in SSR applications
**Options:**
```tsx
hydrate(() => , element, {
renderId: "app", // Optional render ID
owner: undefined, // Optional owner context
});
```
## renderToString - Server Rendering
Render components to HTML string for SSR.
```tsx
import { renderToString } from "solid-js/web";
const html = renderToString(() => );
// Returns: "...
"
```
**Use cases:**
- SSR initial render
- Static site generation
- Email templates
- Server-side HTML generation
## renderToStringAsync - Async Rendering
Render components with async data to HTML string.
```tsx
import { renderToStringAsync } from "solid-js/web";
const html = await renderToStringAsync(() => );
// Waits for async resources
```
**Use cases:**
- SSR with async data
- Resources and Suspense
- Async components
## renderToStream - Streaming SSR
Stream HTML to client for faster time-to-first-byte.
```tsx
import { renderToStream } from "solid-js/web";
const stream = renderToStream(() => );
// Pipe to response
stream.pipeTo(response);
```
**Benefits:**
- Faster initial render
- Progressive HTML delivery
- Better perceived performance
## HydrationScript / generateHydrationScript
Bootstrap hydration before Solid runtime loads.
```tsx
import { HydrationScript, generateHydrationScript } from "solid-js/web";
// As component (JSX)
// As string (manual HTML)
const script = generateHydrationScript({
nonce,
eventNames: ["click", "input"],
});
```
**Purpose:**
- Sets up hydration on client
- Required for SSR apps
- Place once in `` or before closing ``
## isServer - Environment Check
Check if code is running on server.
```tsx
import { isServer } from "solid-js/web";
if (isServer) {
// Server-only code
console.log("Running on server");
} else {
// Client-only code
console.log("Running on client");
}
```
**Use cases:**
- Conditional server/client code
- Environment-specific logic
- Avoiding browser APIs on server
## Common Patterns
### Client Entry Point
```tsx
// entry-client.tsx
import { render } from "solid-js/web";
import App from "./App";
render(() => , document.getElementById("app")!);
```
### SSR Entry Point
```tsx
// entry-server.tsx
import { renderToString, generateHydrationScript } from "solid-js/web";
import App from "./App";
export default function handler(req, res) {
const html = renderToString(() => );
res.send(`
${generateHydrationScript()}
${html}
`);
}
```
### Client Hydration
```tsx
// entry-client.tsx
import { hydrate } from "solid-js/web";
import App from "./App";
hydrate(() => , document.getElementById("app")!);
```
### Streaming SSR
```tsx
import { renderToStream } from "solid-js/web";
export default async function handler(req, res) {
const stream = renderToStream(() => );
res.setHeader("Content-Type", "text/html");
stream.pipeTo(res);
}
```
### Environment-Specific Code
```tsx
import { isServer } from "solid-js/web";
function Component() {
if (isServer) {
// Server-only initialization
return Server rendered
;
}
// Client-only code
const [mounted, setMounted] = createSignal(false);
onMount(() => setMounted(true));
return Client: {mounted()}
;
}
```
## Best Practices
1. **Always use function form:**
- `render(() => , element)`
- Not `render(, element)`
2. **Empty mount element:**
- Element should be empty
- Render appends, dispose removes all
3. **Hydration matching:**
- Server and client must match
- Same structure and content
4. **Use isServer checks:**
- Avoid browser APIs on server
- Conditional logic when needed
5. **Streaming for performance:**
- Use renderToStream for SSR
- Faster time-to-first-byte
## Summary
- **render**: Client-side mounting
- **hydrate**: SSR hydration
- **renderToString**: Server HTML generation
- **renderToStringAsync**: Async server rendering
- **renderToStream**: Streaming SSR
- **HydrationScript / generateHydrationScript**: Hydration setup
- **isServer**: Environment detection