React-HOOKs的setState的使用

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1、数字类型

import React, { useState } from 'react';

const Index = ()=> {
  const [count, setCount] = useState(0);

  return (
    <>
      <h2>{count}</h2>
      <button onClick={()=>(setCount(count+1))}>Add</button>
    </>
  );
}

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2、对象类型

import React, { useState } from 'react';

const Index = ()=> {
  const [obj, setObj] = useState({name:"zhangsan"});

  return (
    <>
      <h2>{obj.name}---{obj.age}</h2>	  
      <button onClick={()=> (
		setObj({
		  ...obj,
		  age:18
		})
	  )}>change-obj</button>
    </>
  );
}

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3、数组类型

import React, { useState } from 'react';

const Index = ()=> {
  const [arr, setArr] = useState([1,2,3]);

  return (
    <>

      <h2>{arr}</h2>
      <button onClick={()=>(setArr(
		setarr(()=> {
		  arr.push(4);
		  return [...arr]
		})>change-arr</button>

    </>
  );
}

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4、函数类型

import React, { useState } from 'react';

const Index = ()=> {
  const [func, setFunc] = useState(()=> {
	return {name:'lisi'}
  });

  return (
    <>
	 <h2>{func}</h2>
    </>
  );
}

• 这里的 func 指的是函数的返回值，如果返回数字类型，那就是数字，返回对象类型，那就是对象

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