在 React useCallback hook 中，回调函数中的参数从哪里来

Question

Suppose i have a useCallback function like this

export const useMenu = (id1, id2, id3) => useCallback(({row, column, id}, myProps) => {
    doSomething()
}, [id1, id2, id3]);

And I'm calling the useMenu function like this

const myMenu = useMenu(123, 345, 567);

So i just wanted to understand from where am i getting this row , column and myProps's value?

Answer 1

They're parameters that must get passed to the myMenu function when invoked later, eg with myMenu({ row: 123 }) . See below snippet for an example:

 const useMenu = (id1, id2, id3) => React.useCallback(({row, column, id}, myProps) => { console.log('got row of', row); }, [id1, id2, id3]); const App = ({ id1, id2, id3 }) => { const myMenu = useMenu(123, 345, 567); React.useEffect(() => { myMenu({ row: 123 }); }, []); return 'app'; }; ReactDOM.render(<App />, document.querySelector('.react'));

 <script crossorigin src="https://unpkg.com/react@16/umd/react.development.js"></script> <script crossorigin src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script> <div class="react"></div>

For your code, look to see what calls myMenu to see exactly where the parameters come from.