React - how to call function with useEffect only once

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Asked by:

567

React useEffect hook runs the passed function on every component change or when anything in the array of dependencies changes.

What if I want to call initializeData function like in the class components componentDidMount method and not call it again on change?

my component:

const App = () => {
  useEffect(() => {
      initializeData(); 
  });
  return (
    <div>
      ...
    </div>
  );
}

1 answer

0 points

Answered by:

567

I've read about it and prepared the solution:

You need to create useEffect hook with an empty array of dependencies. That tells React to execute the effect only once (at component mount).

Solution:

const App = () => {
  useEffect(() => {
      initializeData(); 
  }, []);
  return (
    <div>
      ...
    </div>
  );
}

Note:

Check our React - useEffect hook atricle for more runnable examples.

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