（一）需要
最近在学习React，学到了React Hook 做了useState Demo。
（二）介绍
1、默认值是数字类型
const [num, setNum] = useState(0);const clickX = () => { setNum(num + 1);}<p> 1、初始化为数字:{num}</p><Button onClick={clickX}> Click Number</Button>2、默认值是对象类型
初始化为对象是用构造复制的模式const [obj, setObj] = useState({ a: 1 });const clickObj = () => { setNum(num + 1); setObj({ ...obj, b: num + 1 });}<p> 2、初始化为对象: a-{obj.a} ;b-{obj.b}</p><Button onClick={clickObj}> Click Object</Button>（三）实现Demo
/* * @Author: ArdenZhao * @Date: 2022-04-14 16:46:18 * @LastEditTime: 2022-04-14 17:06:55 * @FilePath: /react-ts/src/components/react/7-Hook-useState.js * @Description: file information */import React, { useState, useCallback } from 'react';import { Button } from 'antd';import "antd/dist/antd.css";function HookUseState(props) { // useState 不能放在函数外部，这里设置初始值为0 const [num, setNum] = useState(0); const [obj, setObj] = useState({ a: 1 }); const clickX = () => { setNum(num + 1); } const clickObj = () => { setNum(num + 1); setObj({ ...obj, b: num + 1 }); } return ( <div> <h1>Learn, {props.name}</h1> <p> 1、初始化为数字:{num} </p> <Button onClick={clickX}> Click Number </Button> <p> 2、初始化为对象: a-{obj.a} ;b-{obj.b} </p> <Button onClick={clickObj}> Click Object </Button> </div> );}export default HookUseState// 参考链接// https://flaviocopes.com/react-hook-usecallback/写在最初的话
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