Handling API calls using useEffect vs using useCallback

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This is very likely a dumb question -- I have the understanding that anything that triggers a side-effect should be handled with useEffect. I was wondering if that understanding is correct. Particularly in the context of making an API call -- is it good to make API calls in a useCallback hook?

usecallback use-effect react-hooks reactjs side-effects
1 Answers

If you want to do it based on some kind of prop or state change, use the useEffect hook, e.g.,

useEffect(async ()=> {
    const user = await userApi.get(props.id)
    
    setUser(user)
}, [props.id]}

If you want to do so on a button click (or any event),

const handleClick = () => {
    const user = await userApi.get(props.id)
        
    setUser(user)
}

useCallback isn't really relied on for api calls or side-effects. useCallback is basically storing a "version" of a function, based on dependencies. When a dependency changes, you get a new function, because what it returns will be different, e.g.,

// props.id = 1
const doSomethingCallback = useCallback(() => { 
    /* do something with props.id */
}, [props.id])

While props.id === 1, doSomethingCallback will always reference the function as it was declared on the first render. If props.id changes to 2, useCallback will reference a new function. So, if doSomethingCallback was a dependency of a useEffect, when props.id changed to 2, useCallback would point to a new function, which would then get noticed by the useEffect and run whatever was in it, e.g.,

useEffect(() => { /* side-effect stuff */}, [doSomethingCallback])

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