react hook useEffect 无限循环

Question

Below is my code snipet. When i receieve my prop and try to useSate, i recieve this infine loop even after following number of solutions.

const App = ({ center }) => {
  const position = [-1.29008, 36.81987];

  const [mapCenter, setMapCenter] = useState();

  useEffect(() => {
    if (center && center.length > 0) setMapCenter(center);
    else setMapCenter(position);
  }, [center, position]);


return (<div> </div>)

}

export default App;

Answer 1

The issue is that you are defining position array in functional component and its reference gets changed on each re-render and hence the useEffect executed again.

You can move declaration of position out of component since its a constant like

const position = [-1.29008, 36.81987];
const App = ({ center }) => {


  const [mapCenter, setMapCenter] = useState();

  useEffect(() => {
    if (center && center.length > 0) setMapCenter(center);
    else setMapCenter(position);
  }, [center, position]);


return (<div> </div>)

}

export default App;

or remove the dependency of position from useEffect

const App = ({ center }) => {
  const position = [-1.29008, 36.81987];

  const [mapCenter, setMapCenter] = useState();

  useEffect(() => {
    if (center && center.length > 0) setMapCenter(center);
    else setMapCenter(position);
  }, [center]);


return (<div> </div>)

}

export default App;

Answer 2

remove the dependency of position from useEffect