feat(vite): experimental rsc plugin support

examples/vite-rsc/.gitignore

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+node_modules
+dist

examples/vite-rsc/README.md

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+# Vite + RSC + Nitro Example
+
+Copied from https://github.com/vitejs/vite-plugin-react/tree/main/packages/plugin-rsc/examples/starter
+
+The difference from the original template is to export `default.fetch` handler from `entry.ssr.tsx` instead of `entry.rsc.tsx`.

examples/vite-rsc/app/action.tsx

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+"use server";
+
+let serverCounter = 0;
+
+export async function getServerCounter() {
+  return serverCounter;
+}
+
+export async function updateServerCounter(change: number) {
+  serverCounter += change;
+}

examples/vite-rsc/app/client.tsx

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+"use client";
+
+import React from "react";
+
+export function ClientCounter() {
+  const [count, setCount] = React.useState(0);
+
+  return (
+    <button onClick={() => setCount((count) => count + 1)}>
+      Client Counter: {count}
+    </button>
+  );
+}

examples/vite-rsc/app/framework/entry.browser.tsx

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+import {
+  createFromReadableStream,
+  createFromFetch,
+  setServerCallback,
+  createTemporaryReferenceSet,
+  encodeReply,
+} from "@vitejs/plugin-rsc/browser";
+import React from "react";
+import { createRoot, hydrateRoot } from "react-dom/client";
+import { rscStream } from "rsc-html-stream/client";
+import { GlobalErrorBoundary } from "./error-boundary";
+import type { RscPayload } from "./entry.rsc";
+import { createRscRenderRequest } from "./request";
+
+async function main() {
+  // Stash `setPayload` function to trigger re-rendering
+  // from outside of `BrowserRoot` component (e.g. server function call, navigation, hmr)
+  let setPayload: (v: RscPayload) => void;
+
+  // Deserialize RSC stream back to React VDOM for CSR
+  const initialPayload = await createFromReadableStream<RscPayload>(
+    // Initial RSC stream is injected in SSR stream as <script>...FLIGHT_DATA...</script>
+    rscStream
+  );
+
+  // Browser root component to (re-)render RSC payload as state
+  function BrowserRoot() {
+    const [payload, setPayload_] = React.useState(initialPayload);
+
+    React.useEffect(() => {
+      setPayload = (v) => React.startTransition(() => setPayload_(v));
+    }, [setPayload_]);
+
+    // Re-fetch/render on client side navigation
+    React.useEffect(() => {
+      return listenNavigation(() => fetchRscPayload());
+    }, []);
+
+    return payload.root;
+  }
+
+  // Re-fetch RSC and trigger re-rendering
+  async function fetchRscPayload() {
+    const renderRequest = createRscRenderRequest(globalThis.location.href);
+    const payload = await createFromFetch<RscPayload>(fetch(renderRequest));
+    setPayload(payload);
+  }
+
+  // Register a handler which will be internally called by React
+  // on server function request after hydration.
+  setServerCallback(async (id, args) => {
+    const temporaryReferences = createTemporaryReferenceSet();
+    const renderRequest = createRscRenderRequest(globalThis.location.href, {
+      id,
+      body: await encodeReply(args, { temporaryReferences }),
+    });
+    const payload = await createFromFetch<RscPayload>(fetch(renderRequest), {
+      temporaryReferences,
+    });
+    setPayload(payload);
+    const { ok, data } = payload.returnValue!;
+    if (!ok) throw data;
+    return data;
+  });
+
+  // Hydration
+  const browserRoot = (
+    <React.StrictMode>
+      <GlobalErrorBoundary>
+        <BrowserRoot />
+      </GlobalErrorBoundary>
+    </React.StrictMode>
+  );
+  if ("__NO_HYDRATE" in globalThis) {
+    createRoot(document).render(browserRoot);
+  } else {
+    hydrateRoot(document, browserRoot, {
+      formState: initialPayload.formState,
+    });
+  }
+
+  // Implement server HMR by triggering re-fetch/render of RSC upon server code change
+  if (import.meta.hot) {
+    import.meta.hot.on("rsc:update", () => {
+      fetchRscPayload();
+    });
+  }
+}
+
+// A little helper to setup events interception for client side navigation
+function listenNavigation(onNavigation: () => void) {
+  globalThis.addEventListener("popstate", onNavigation);
+
+  const oldPushState = globalThis.history.pushState;
+  globalThis.history.pushState = function (...args) {
+    const res = oldPushState.apply(this, args);
+    onNavigation();
+    return res;
+  };
+
+  const oldReplaceState = globalThis.history.replaceState;
+  globalThis.history.replaceState = function (...args) {
+    const res = oldReplaceState.apply(this, args);
+    onNavigation();
+    return res;
+  };
+
+  function onClick(e: MouseEvent) {
+    const link = (e.target as Element).closest("a");
+    if (
+      link &&
+      link instanceof HTMLAnchorElement &&
+      link.href &&
+      (!link.target || link.target === "_self") &&
+      link.origin === location.origin &&
+      !link.hasAttribute("download") &&
+      e.button === 0 && // left clicks only
+      !e.metaKey && // open in new tab (mac)
+      !e.ctrlKey && // open in new tab (windows)
+      !e.altKey && // download
+      !e.shiftKey &&
+      !e.defaultPrevented
+    ) {
+      e.preventDefault();
+      history.pushState(null, "", link.href);
+    }
+  }
+  document.addEventListener("click", onClick);
+
+  return () => {
+    document.removeEventListener("click", onClick);
+    globalThis.removeEventListener("popstate", onNavigation);
+    globalThis.history.pushState = oldPushState;
+    globalThis.history.replaceState = oldReplaceState;
+  };
+}
+
+// eslint-disable-next-line unicorn/prefer-top-level-await
+main();

examples/vite-rsc/app/framework/entry.rsc.tsx

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+import {
+  renderToReadableStream,
+  createTemporaryReferenceSet,
+  decodeReply,
+  loadServerAction,
+  decodeAction,
+  decodeFormState,
+} from "@vitejs/plugin-rsc/rsc";
+import type { ReactFormState } from "react-dom/client";
+import { Root } from "../root.tsx";
+import { parseRenderRequest } from "./request.tsx";
+
+// The schema of payload which is serialized into RSC stream on rsc environment
+// and deserialized on ssr/client environments.
+export type RscPayload = {
+  // this demo renders/serializes/deserializes entire root html element
+  // but this mechanism can be changed to render/fetch different parts of components
+  // based on your own route conventions.
+  root: React.ReactNode;
+
+  // Server action return value of non-progressive enhancement case
+  returnValue?: { ok: boolean; data: unknown };
+
+  // Server action form state (e.g. useActionState) of progressive enhancement case
+  formState?: ReactFormState;
+};
+
+// The plugin by default assumes `rsc` entry having default export of request handler.
+// however, how server entries are executed can be customized by registering own server handler.
+export default async function handler(request: Request): Promise<Response> {
+  // Differentiate RSC, SSR, action, etc.
+  const renderRequest = parseRenderRequest(request);
+  request = renderRequest.request;
+
+  // Handle server function request
+  let returnValue: RscPayload["returnValue"] | undefined;
+  let formState: ReactFormState | undefined;
+  let temporaryReferences: unknown | undefined;
+  let actionStatus: number | undefined;
+
+  if (renderRequest.isAction === true) {
+    if (renderRequest.actionId) {
+      // Action is called via `ReactClient.setServerCallback`.
+      const contentType = request.headers.get("content-type");
+      const body = contentType?.startsWith("multipart/form-data")
+        ? await request.formData()
+        : await request.text();
+      temporaryReferences = createTemporaryReferenceSet();
+      const args = await decodeReply(body, { temporaryReferences });
+      const action = await loadServerAction(renderRequest.actionId);
+      try {
+        // eslint-disable-next-line prefer-spread
+        const data = await action.apply(null, args);
+        returnValue = { ok: true, data };
+      } catch (error_) {
+        returnValue = { ok: false, data: error_ };
+        actionStatus = 500;
+      }
+    } else {
+      // Otherwise server function is called via `<form action={...}>`
+      // before hydration (e.g. when JavaScript is disabled).
+      // aka progressive enhancement.
+      const formData = await request.formData();
+      const decodedAction = await decodeAction(formData);
+      try {
+        const result = await decodedAction();
+        formState = await decodeFormState(result, formData);
+      } catch {
+        // there's no single general obvious way to surface this error,
+        // so explicitly return classic 500 response.
+        return new Response("Internal Server Error: server action failed", {
+          status: 500,
+        });
+      }
+    }
+  }
+
+  // Serialization from React VDOM tree to RSC stream.
+  // We render RSC stream after handling server function request
+  // so that new render reflects updated state from server function call
+  // to achieve single round trip to mutate and fetch from server.
+  const rscPayload: RscPayload = {
+    root: <Root url={renderRequest.url} />,
+    formState,
+    returnValue,
+  };
+
+  const rscOptions = { temporaryReferences };
+  const rscStream = renderToReadableStream<RscPayload>(rscPayload, rscOptions);
+
+  // Respond RSC stream without HTML rendering as decided by `RenderRequest`
+  if (renderRequest.isRsc) {
+    return new Response(rscStream, {
+      status: actionStatus,
+      headers: {
+        "content-type": "text/x-component;charset=utf-8",
+      },
+    });
+  }
+
+  // Delegate to SSR environment for HTML rendering.
+  // The plugin provides `loadModule` helper to allow loading SSR environment entry module
+  // in RSC environment. however this can be customized by implementing own runtime communication
+  // e.g. `@cloudflare/vite-plugin`'s service binding.
+  const ssrEntryModule = await import.meta.viteRsc.loadModule<
+    typeof import("./entry.ssr.tsx")
+  >("ssr", "index");
+
+  const ssrResult = await ssrEntryModule.renderHTML(rscStream, {
+    formState,
+    // Allow quick simulation of JavaScript disabled browser
+    debugNoJS: renderRequest.url.searchParams.has("__nojs"),
+  });
+
+  // Respond HTML
+  return new Response(ssrResult.stream, {
+    status: ssrResult.status,
+    headers: {
+      "Content-Type": "text/html",
+    },
+  });
+}
+
+if (import.meta.hot) {
+  import.meta.hot.accept();
+}