prevstate in usestate
const [prevState, setState] = React.useState([]);
setState(prevState => [...prevState, 'somedata'] );prevstate in usestate
const [prevState, setState] = React.useState([]);
setState(prevState => [...prevState, 'somedata'] );this.setstate prevstate
this.setState(prevState => ({ n: !prevState.n }))when to use previous state in useState
import React, { useState } from "react";
import ReactDOM from "react-dom";
function Counter() {
const [count, setCount] = useState(0);
return (
<div>
<h1>{count}</h1>
<button onClick={() => setTimeout(() => setCount(count + 1), 2000)}>
Delayed Counter (basic)
</button>
<button onClick={() => setTimeout(() => setCount(x => x + 1), 2000)}>
Delayed Counter (functional)
</button>
<button onClick={() => setCount(count + 1)}>Immediate Counter</button>
</div>
);
}
const rootElement = document.getElementById("root");
ReactDOM.render(<Counter />, rootElement);Copyright © 2021 Codeinu
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