Streaming

Kaito supports streaming out of the box we let you return a Response with a ReadableStream body, but we also have built-in utilities for doing server-sent events (SSE).

SSE

SSE is a technology that allows you to stream data to the client in realtime. It’s a very simple protocol. You can learn about it on MDN.

Kaito has a built-in utility for doing SSE, called sse. This function returns a Response object that you can return from your route.

const stream = router().get('/', async ({ctx}) => {
	return sse(async function* () {
		yield {data: 'Hello, world!'};
		await new Promise(resolve => setTimeout(resolve, 1000));
		yield {data: 'Hello, world!'};
	});
});

Basic streaming

You can also just return a response with a ReadableStream body.

router().get('/', async () => {
	const stream = new ReadableStream<string>({
		async start(controller) {
			controller.enqueue('Hello, ');
			await sleep(1000);
			controller.enqueue('world!');
			await sleep(1000);
			controller.close();
		},
	});
 
	return new Response(stream, {
		headers: {'Content-Type': 'text/plain'},
	});
});

Client Error Handling