reelevant-tech/react-hooks-sse

Subscribe to an SSE endpoint with React Hooks

React Hooks SSE

Installation

yarn add react-hooks-sse

Usage

import React from 'react';
import { useSSE, SSEProvider } from 'react-hooks-sse';

const Comments = () => {
  const state = useSSE('comments');

  return state ? state.data.value : '...';
};

const App = () => (
  <SSEProvider endpoint="https://sse.example.com">
    <h1>Subscribe & update to SSE event</h1>
    <Comments />
  </SSEProvider>
);

Checkout the example on the project

API

SSEProvider

The provider manage the subscritpion to the SSE server. You can subscribe multiple times to the same event or on different events. The source is created only once when one of the hook is called inside the tree. The source is destroyed when no more hooks are registered.

Options

Name	Type	Required	Default	Description
endpoint	string	true	-	The SSE endpoint to target on the server.
options	object	false	{ withCredentials: false }	See EventSource documentation.

Usage

import React from 'react';
import { SSEProvider } from 'react-hooks-sse';

const App = () => (
  <SSEProvider
    endpoint="https://sse.example.com"
    options={{
      withCredentials: true
    }}
  >
    {/* ... */}
  </SSEProvider>
);

useSSE

The component that uses the hook must be scoped under a SSEProvider to have access to the source. Once the hook is created none of the options can be updated (at the moment). You have to unmout / remount the component to update the options.

Name	Type	Required	Default	Description
eventName	string	true	-	The name of the event that you want to listen.
options	object	false	-	-
options.initialState	T	false	null	The initial state to use on the first render.
options.stateReducer	(state: T, changes: U) => T	false	(state, changes) => changes	The state reducer to control how the state should be updated.
options.parser	(input: string) => U	false	(input) => JSON.parse(input)	The parser to control how the event from the server is provided to the reducer.

Usage

import React from 'react';
import { useSSE } from 'react-hooks-sse';

const Comments = () => {
  const state = useSSE('comments', {
    initialState: {
      data: {
        value: null,
      },
    },
    stateReducer(state, changes) {
      // changes.event - event provided by the source
      // changes.data - data provided by the parser

      return changes;
    },
    parser(input) {
      return JSON.parse(input);
    },
  });

  return <p>{state.data.value !== null && <span>{state.data.value}</span>}</p>;
};

Run example

yarn start:server

yarn start:example

Run the build

yarn build

Run the test

yarn test