import React, { useEffect, use - 大眼睛图图 - 沸点 - 掘金

1年前

import React, { useEffect, useState } from "react";

function App() {
const [appNum, setAppNum] = useState(100);

console.log("父组件更新了");

const SonComponent = React.memo(function Son() {
console.log("SonComponent 更新了");
return <div>SonComponent</div>;
});

useEffect(() => {
setTimeout(() => {
setAppNum(150);
}, 3000);
}, []);

return (
<div className="App">
this is app {appNum}
<SonComponent />
</div>
);
}

export default App; 为什么这段代码用了React.memo不生效而把SonComponent组件单独放在另一个文件中却能生效？

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