React 组件重新渲染

Question

I'm learning react and I'm building this project that currently is very small but the Products component keep re-rendering.

As you can see I have a console.log(products); and in the console i see it printing 4 times.

How can I avoid this re-rendering?

1. []
2. []
3. [...data here]
4. [...data here]

Network tab only shows one call to fetch the data. So that's good.

APP.JS

const app = () => {
  return (
    <div className="App">
      <Products />
    </div>
  );
}

PRODUCTS.JS

const Products = props => {

    const products = useSelector(state => state.products);
    const dispatch = useDispatch();
    const onLoadProducts = useCallback(() => dispatch(actionCreators.onLoadProducts()), [dispatch]);


    useEffect(() => {
        onLoadProducts();
    }, [onLoadProducts]);

    const flag = products.length > 0 ? 'YAY' : 'NAY';
    console.log(products);
    return (
        <p>{flag}</p>
    )
}

export default React.memo(Products);

INDEX.JS

const composeEnhancers = process.env.NODE_ENV === 'development' ? window.__REDUX_DEVTOOLS_EXTENSION_COMPOSE__ : null || compose;

const store = createStore(productsReducer, composeEnhancers(
  applyMiddleware(thunk)
));

ReactDOM.render(
  <React.StrictMode>
    <Provider store={store}><App /></Provider>
  </React.StrictMode>,
  document.getElementById('root')
);

Answer 1

Remove the <React.StrictMode> Comp. It should fix the issue.

Please check this issue. This answers your question here