release: WRNexusJS 0.3.0

packages/ssr/src/index.ts

@@ -177,3 +177,62 @@ function resolveSeoUrl(
     return value;
   }
 }
+
+export interface StreamRenderOptions extends Omit<RenderOptions, "body"> {
+  body: string | Promise<string> | AsyncIterable<string>;
+}
+
+function isAsyncIterable(value: unknown): value is AsyncIterable<string> {
+  return (
+    typeof value === "object" &&
+    value !== null &&
+    Symbol.asyncIterator in value &&
+    typeof (value as AsyncIterable<string>)[Symbol.asyncIterator] === "function"
+  );
+}
+
+async function* bodyChunks(body: StreamRenderOptions["body"]): AsyncIterable<string> {
+  if (typeof body === "string") {
+    yield body;
+    return;
+  }
+  if (isAsyncIterable(body)) {
+    yield* body;
+    return;
+  }
+  yield await body;
+}
+
+/**
+ * Stream a complete document while preserving the exact head/body contract of
+ * `renderDocument`. Async iterables can flush a shell, primary content, and
+ * slower fragments without buffering the entire route.
+ */
+export function renderDocumentStream(opts: StreamRenderOptions): ReadableStream<Uint8Array> {
+  const marker = "<!--__WRNEXUS_STREAM_BODY__-->";
+  const document = renderDocument({ ...opts, body: marker });
+  const [prefix, suffix] = document.split(marker);
+  const encoder = new TextEncoder();
+
+  return new ReadableStream<Uint8Array>({
+    async start(controller) {
+      try {
+        controller.enqueue(encoder.encode(prefix ?? ""));
+        for await (const chunk of bodyChunks(opts.body)) controller.enqueue(encoder.encode(chunk));
+        controller.enqueue(encoder.encode(suffix ?? ""));
+        controller.close();
+      } catch (error) {
+        controller.error(error);
+      }
+    },
+  });
+}
+
+export function streamDocumentResponse(
+  opts: StreamRenderOptions,
+  init: ResponseInit = {},
+): Response {
+  const headers = new Headers(init.headers);
+  if (!headers.has("content-type")) headers.set("content-type", "text/html; charset=utf-8");
+  return new Response(renderDocumentStream(opts), { ...init, headers });
+}