react-context-with-selector
v1.0.1
Published
use React Context with selector
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react-context-with-selector
use React Context with selector
Introduction
When the value of React Context changes, all components that use useContext are re-rendered. This causes unnecessary re-rendering.
Using this library, can solve this issue.
Install
This package has peer dependencies, which you need to install by yourself.
// npm
npm install use-context-selector react
// yarn
yarn add use-context-selector react
Usage
import { memo, useCallback, useMemo, useState } from "react";
import { createContext } from "react-context-with-selector";
const CountContext = createContext({
count: 0,
count2: 0,
increment: () => {},
increment2: () => {},
});
const Counter = memo(() => {
const count = CountContext.useContext((state) => state.count);
const increment = CountContext.useContext((state) => state.increment);
return (
<div>
<span>Count: {count}</span>
<button type="button" onClick={increment}>
increment
</button>
</div>
);
});
const Counter2 = memo(() => {
const count = CountContext.useContext((state) => state.count2);
const increment = CountContext.useContext((state) => state.increment2);
return (
<div>
<span>Count: {count}</span>
<button type="button" onClick={increment}>
increment
</button>
</div>
);
});
const CounterContainer = () => {
const [count, setCount] = useState(0);
const [count2, setCount2] = useState(0);
const increment = useCallback(() => {
setCount((_count) => _count + 1);
}, []);
const increment2 = useCallback(() => {
setCount2((_count) => _count + 1);
}, []);
const contextValues = useMemo(
() => ({ count, increment, count2, increment2 }),
[count, count2, increment, increment2]
);
return (
<CountContext.Provider value={contextValues}>
<Counter />
<Counter2 />
</CountContext.Provider>
);
};