react-hook-signal



> React-Hook-Signal is a tiny library, less than 1kb. It helps you integrate Signal with your React components easily.

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``bash
npm install react-hook-signal signal-polyfill
`

What are Signals?

The TC39 Proposal for Signals in JavaScript aims to establish a mechanism for components to communicate effectively. This proposal includes a polyfill for prototyping purposes.

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- Refer to https://eisenbergeffect.medium.com/a-tc39-proposal-for-signals-f0bedd37a335 for detailed explanation.
- Explore the proposal repository: https://github.com/proposal-signals/proposal-signals

Once adopted, JavaScript will have a native signaling system, referred to as Signal throughout this guide.

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!Solving rerendering problem in react using signal

In React components, re-rendering starts at the component's beginning and extends to the end of the JSX element. Signal usage allows precise re-rendering, boosting performance and simplifying development without the need for memoization or useCallback functions.

Why choose React-Hook-Signal?

- It's straightforward: Just React and Native Signal, no extra babel plugin needed.
- Enjoy full TypeScript support for an improved Developer Experience.
- Flexibility is key: Opt-in for integration in your React project, seamlessly blending state and signal.
- It's incredibly lightweight, clocking in at less than 1kb

Steps to Integrate Signals with React

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- Utilize notifiable components provided by react-hook-signal.
- notifiable components accept standard HTML attributes, Signal, and Lambda for detecting dependency changes.

Example:
`tsx
// Global.tsx
import {Signal} from "signal-polyfill";
import {JSXAttribute} from "react-hook-signal";

export const count = new Signal.State(0)
export const renderCount = new Signal.Computed(() => {
return

Count {count.get()}

})

`
The fastest way to integrate these Signals is to use the notifiable components.

`tsx
import {count,renderCount} from "./GlobalSignals.tsx";
// here we are importing react-hook-signal:notifiable
import {notifiable} from "react-hook-signal";


export function App() {
return <>

{/ When user click button it will update the state /}
count.set(count.get() + 1)}>Click here

{/ Following line will get auto update when user click button/}
{renderCount}

}
`

notifiable component attributes is not only capable of accepting the Signal type but also can receive Lambda

> Lambda is a callback that's able to listen for changes in the signals it depends on.

`tsx
import {count} from "./GlobalSignals.tsx";
import {notifiable} from "react-hook-signal";


export function App() {
return <>

{/ When user click button it will update the state /}
count.set(count.get() + 1)}>Click here

{/ Following line will get auto update when user click button/}
{() => {
return

Count {count.get()}

}}

}
`

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- Use the useSignalEffect hook to listen for changes in Signal.
- This hook accepts a callback that reads the final signal value and can optionally return a cleanup function.

#### Important Note:

- useSignalEffect doesn't automatically re-render the component. Use React.useState to trigger a re-render.

Example:

`tsx
import {count} from "./GlobalSignals.tsx";
import {useSignalEffect} from "react-hook-signal";
import {useState} from "react";

export function App() {
const [countState,setCountState] = useState(count.get())

useSignalEffect(() => {
// Here, within the useSignalEffect hook, I can listen for updates on any Signal.State or Signal.Computed
setCountState(count.get())
})
return

{/ When user click button it will update the state /}
count.set(count.get() + 1)}>Click here

{/ Following line will be updated because of countState updated/}

{countState}

}

`

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- useSignal is a hook that creates Signal.State, and useComputed is a hook that creates Signal.Computed.
- These hooks generate signals that are linked to the component's lifecycle.

- To create a Signal.State, simply provide a constant value as a parameter when calling useSignal.
- To create a Signal.Computed,simply provide a Lambda that returns the result of a dynamic computation.

Example :
`tsx
import {notifiable, useSignal, useComputed} from "react-hook-signal";

export function App() {

// creating Signal.State count
const count = useSignal(0);

// creating Signal.Computed countString
const countString = useComputed(() => (count.get() * 2).toString());

// creating Signal.Computed style
const style = useComputed(() => {
const isEven = count.get() % 2 === 0;
return {
background: isEven ? 'white' : 'black',
color: isEven ? 'black' : 'white'
}
})

// creating Signal.Computed text
const text = useComputed(() => {
const isWhite = style.get().background === 'white'
return

{isWhite ? 'Background is White' : 'Background is Black'}

})

return

{/ When user click button it will update the state /}
count.set(count.get() + 1)}>Click here

{/ Following line will never get auto update/}

{countString.get()}

{/ Following line will get auto update when user click button/}
{countString}

{/ Following line will get auto update when user click button/}
{text}

}

`

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- Use Notifiable component to wrap any React Functional or Class Component
- A React component encapsulated within the Notifiable component will inherently enable its properties and children to utilize Lambda expressions or Signals seamlessly

Example :
`tsx
import {Notifiable} from "react-hook-signal";

export function App() {
const count = useSignal(0);

return

{/ When user click button it will update the state /}
count.set(count.get() + 1)}>Click here

{/ Following line will be updated because of count updated/}
{
return count.get() + ' Times'
}}>

}

function MyComponent(props:{title:string}){
return

Here is the title {props.title}

}
`

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The integration of Signal` into the React application can be done in various ways tailored to the needs and complexity of the app.