useSSE

useSSE is abbreviation for use server-side effect. It is a custom React hook to perform asynchronous effects both on client and serve side.

npm i use-sse

Usage

Use useSSE to fetch data in component:

import React from "react";
import { useSSE } from "use-sse";

const MyComponent = () => {
  const [data, error] = useSSE(() => {
    return fetch("https://myapi.example.com").then((res) => res.json());
  }, []);

  return <div>{data.title}</div>;
};

All effects will be resolved on server side during rendering.

This is a part of server side render phase. Se an example for the whole code.

const { ServerDataContext, resolveData } = createServerContext();

// We need to render app twice.
// First - render App to reqister all effects
renderToString(
  <ServerDataContext>
    <App />
  </ServerDataContext>
);

// Wait for all effects to finish
const data = await resolveData();

// Inject into html initial data
res.write(data.toHtml());

// Render App for the second time
// This time data form effects will be avaliable in components
const htmlStream = renderToNodeStream(
  <ServerDataContext>
    <App />
  </ServerDataContext>
);

On client side of application use BroswerDataContext:

// This will create context will all data fetched during server side rendering
const BroswerDataContext = createBroswerContext();

hydrate(
  <BroswerDataContext>
    <App />
  </BroswerDataContext>,
  document.getElementById("app")
);

API

useSSE

const [data, error] = useSSE(effect, dependencies);

Params

param	type	required	description	example
effect	() => Promise<any>	true	effect function returning promise which resolves to data	() => fetch('example.com').then(res=>res.json())
dependencies	any[]	false	list of dependencies like in useEffect	[]

Returns

Returns an array with two elements [data, error].

• data - resolved response from effect
• error - an error if effect rejected or if timeout happend.

---

createServerContext()

Creates server side context.

const { ServerDataContext, resolveData } = createServerContext();

Returns

ServerDataContext - React context provider component.

<ServerDataContext>
  <App />
</ServerDataContext>

resolveData - function to resolve all effects.

const data = await resolveData(timeout);

param	type	required	default value	description
timeout	number	false	undefined	max number of ms to wait for effects to resolve

data is an object containing value of context.

Calling data.toHtml(variableName) will return a html script tak with stringified data:

param	type	required	default value	description
variableName	string	false	_initialDataContext	name of global variable

data.toHtml();
// "<script>window._initialDataContext = { context data };</script>"

Both should be used in server side render function.

---

createBroswerContext()

Creates client side context.

createBroswerContext(variableName);

params

param	type	required	default value	description
variableName	string	false	_initialDataContext	name of global variable

returns

BroswerDataContext - React context provider for client side application

<BroswerDataContext>
  <App />
</BroswerDataContext>

Examples

See example directory for React with SSR and useSSE.

The same example is avaliable on CodeSandbox.