React函数式组件Hook中的useState函数的详细解析

import React from 'react'
function App1(){
    return (
        <div>
            <h1>函数式组件</h1>
        </div>
    )
}
export default App1;

import React from 'react';
const App = () => {
    return (
        <div>
            
        </div>
    );
}
export default App;

import ReactDOM from 'react-dom'
import App from './App1'
ReactDOM.render(
    <App />,
    document.getElementById('root')
)

// useState就是hooks提供的一个api
import React, { useState } from 'react'
function App(){
  	// 这里useState(0)中的0，就是定义num的初始值，setNum是修改num的方法
    const [num, setNum] = useState(0);

    return (
        <div>
            <h2>{num}</h2>
            <button onClick={()=>{setNum(num+1)}}>点击加1</button>
        </div>
    )
}
export default App;