import React, {useEffect, useState} from 'react';
function
App
() {
const
[n, setN]
=
useState
(
0
)
const onClick = () => {
setN
(i => i +
1
)
useEffect
(()=>{
console
.log
(n)
},
[]
)
useEffect
(()=>{
if
(n>
0
){
console
.log
("n变化了")
},
[n]
)
return (
<div className="App">
<button onClick={onClick}>+
1
</button>
export default App;
Cindy
React.js
