我正在尝试制作一个简单的示例,该示例遵循文档https://reactjs.org/docs/hooks-reference.html#usecallback上文档中的React Hooks示例
如果没有useCallback代码,请按以下示例进行查找:
import React, { useCallback } from "react";
function Test(props) {
function doSomething(a, b) {
console.log("doSomething called");
return a + b;
}
return (
<div>
{Array.from({ length: 3 }).map(() => (
<div>{doSomething('aaa','bbb')}</div>
))}
</div>
);
}
export default Test;
Run Code Online (Sandbox Code Playgroud)
但是,当我添加我认为正确的代码useCallback如下时,出现错误(未定义a)
import React, { useCallback } from "react";
function Test(props) {
function doSomething(a, b) {
console.log("doSomething called");
return a + b;
}
const memoizedCallback = useCallback(
() => {
doSomething(a, b);
},
[a, …Run Code Online (Sandbox Code Playgroud)