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I have seen some examples on how to code setState callback. All the examples I have seen are related to class components. My question is how do I write setState callback for a function component?

I have following code for an example

In the following code, after setData is called, due to it's asynchronous nature, I want to attach a call back so that I can perform some operation after setData is complete. Any guidance please...

function MyControl(props){
    const[data,setData] = useState(null);
    useEffect(()=>{
       ///fetch data and assign it
       setData(studentInformation);
      },[]); 
    
     
    return (
             <div> </div>
       )
}
V R
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  • What do you want to do once state is set? Why not just do it next time the component renders, which will be triggered by the update? – jonrsharpe Oct 05 '21 at 20:41

2 Answers2

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That is what useEffect is for - to run code only when certain dependencies change.

useEffect(() => {
  // this will only be called when data has changed
  // run your code here
}, [data]);
larz
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0

You'll have to use another useEffect that will detect changes to your data object and do whatever you want to accomplish there.

Someone asked this questions before. Check this answer.

Josue Lopez
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