better-sse

Dead simple, dependency-less, spec-compliant server-sent events implementat...

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MatthewWid/better-ssebetter-sse

README

Better SSE


A dead simple, dependency-less, spec-compliant server-sent events implementation for Node, written in TypeScript.

This package aims to be the easiest to use, most compliant and most streamlined solution to server-sent events with Node that is framework-agnostic and feature-rich.

Please consider starring the project on GitHub ⭐.

Why use Server-sent Events?


Server-sent events (SSE) is a standardised protocol that allows web-servers to push data to clients without the need for alternative mechanisms such as pinging, long-polling or WebSockets.

Using SSE can allow for significant savings in bandwidth and battery life on portable devices and will work with your existing infrastructure as it operates directly over the HTTP protocol without the need for the connection upgrade that WebSockets require.

Compared to WebSockets it has comparable performance and bandwidth usage, especially over HTTP/2, and natively includes event ID generation and automatic reconnection when clients are disconnected.

Comparison: Server-sent Events vs WebSockets vs Polling
WHATWG standards section for server-sent events
MDN guide to server-sent events

Installation


  1. ```bash
  2. # npm
  3. npm install better-sse

  5. # Yarn
  6. yarn add better-sse

  8. # pnpm
  9. pnpm add better-sse
  10. ```

_Better SSE ships with types built in. No need to install from DefinitelyTyped for TypeScript users!_

Usage


The following example shows usage with Express, but Better SSE works with any web-server framework that uses the underlying Node HTTP module.

See the Recipes section of the documentation for use with other frameworks and libraries.


Use sessions to push events to clients:

  1. ```typescript
  2. // Server
  3. import { createSession } from "better-sse";

  5. app.get("/sse", async (req, res) => {
  6. const session = await createSession(req, res);

  8. session.push("Hello world!");
  9. });
  10. ```

  1. ```typescript
  2. // Client
  3. const sse = new EventSource("/sse");

  5. sse.addEventListener("message", ({ data }) => {
  6. console.log(data);
  7. });
  8. ```


Use channels to send events to many clients at once:

  1. ```typescript
  2. import { createSession, createChannel } from "better-sse";

  4. const channel = createChannel();

  6. app.get("/sse", async (req, res) => {
  7. const session = await createSession(req, res);

  9. channel.register(session);

  11. channel.broadcast("A user has joined.", "join-notification");
  12. });
  13. ```


Loop over sync and async iterables and send each value as an event:

  1. ```typescript
  2. const session = await createSession(req, res);

  4. const list = [1, 2, 3];

  6. await session.iterate(list);
  7. ```


Pipe readable stream data to the client as a stream of events:

  1. ```typescript
  2. const session = await createSession(req, res);

  4. const stream = Readable.from([1, 2, 3]);

  6. await session.stream(stream);
  7. ```


Check the API documentation and live examples for information on getting more fine-tuned control over your data such as managing event IDs, data serialization, event filtering, dispatch controls and more!

Documentation


API documentation, getting started guides and usage with other frameworks is available on GitHub.

Contributing


This library is always open to contributions whether it be code, bug reports, documentation or anything else.

Please submit suggestions, bugs and issues to the GitHub issues page.

For code or documentation changes submit a pull request on GitHub.

Local Development


Install Node:

  1. ```bash
  2. curl -L https://git.io/n-install | bash
  3. n auto
  4. ```

Install pnpm:

  1. ```bash
  2. npm i -g pnpm
  3. ```

Install dependencies:

  1. ```bash
  2. pnpm i
  3. ```

Run tests:

  1. ```bash
  2. pnpm t
  3. ```

License


This project is licensed under the MIT license.