When I have a react hook and inside of it I want to define a function in it, would I better use(当我有一个反应钩子并在其中时，我想在其中定义一个函数，我最好使用)
useEffect(() => {
//...
function handler() {}
//...
}, []);
or the newer const declaration(或较新的const声明)
useEffect(() => {
//...
const handler = () => {}
//...
}, []);
Are both exactly equivalent or are there differences in how Javascript handles these things?(两者完全相同还是Javascript处理这些事情的方式不同？)
If I define a const, it's only valid within the current scope, while defining a function would be valid elsewhere, is this true?(如果我定义一个const，则它仅在当前范围内有效，而定义一个函数在其他地方将有效，这是真的吗？)
Does react need the functions accessible in different scopes or are they staying local in the current hook scope?(React是否需要在不同作用域中可访问的功能，还是在当前的钩子作用域中保持局部功能？)
ask by Supertyp translate from so
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