runWithRenderContext

Kind: Function

Source: src/jsx/context.ts

Part of: Jsx

Establish the request-scoped context store for a render.

resumeStore continues a suspended subtree in the same store on the fallback path (ignored when AsyncLocalStorage is available, where isolation is automatic).

Without AsyncLocalStorage a render can't be followed across await, so the store lives in fallbackStore only during synchronous work (mirroring React's request storage). Reading context after await then finds no store and falls back to the default value — never another request's value.

runWithRenderContext creates the request-scoped context store used while rendering a JSX tree. When AsyncLocalStorage is available, the store remains isolated across asynchronous work; otherwise, the fallback store exists only for synchronous rendering and context reads after await return their default values.

Signature

ts
function runWithRenderContext(callback: () => T, resumeStore: RenderStore): T

Parameters

Returns: T

Diagram

mermaid
graph LR
  Render[Render callback] --> Run[runWithRenderContext]
  Run --> ALS{AsyncLocalStorage available?}
  ALS -->|Yes| RequestStore[Request-scoped async store]
  ALS -->|No| FallbackStore[Temporary fallback store]
  RequestStore --> ContextRead[Context reads]
  FallbackStore --> ContextRead
  FallbackStore --> Cleanup[Restore previous fallback store]

Usage

tsx
import { runWithRenderContext } from './jsx/context';
import { renderPage } from './render';

const html = runWithRenderContext(() => {
  return renderPage(<App />);
});

// Context reads performed during renderPage use this render's store.
return new Response(html, {
  headers: { 'content-type': 'text/html' },
});

AI Coding Instructions

• Wrap each top-level render entry point with runWithRenderContext so context values are scoped to that render.
• Keep fallback-mode context-dependent rendering synchronous; context reads after await use the context default value when AsyncLocalStorage is unavailable.
• Pass resumeStore only when resuming a suspended subtree that must continue with its prior context values.
• Restore the previous fallback store after callback execution so one render cannot expose context values to another render.

Used by

1 reference from 1 file. Each is a place in this repository where the symbol is actually used — go read one rather than trusting an example.

Imported by (1)

• Props — src/jsx/base.ts:27