const value setvalue = react.usestate(0) code example

Example 1: update state in useState hook

// declare state using useState hook.
// someState is set to someInitialState
const [someState, setSomeState] = useState(someInitialState);

// setSomeState updates the current state 
setSomeState(someOtherState);

Example 2: 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);