Performance Optimization with Redux v5.0.0

Exhibit how to utilize the performance improvements in Redux v5.0.0, such as useSelector with shallowEqual or memoization techniques to prevent unnecessary re-renders.

import { useSelector, shallowEqual } from 'react-redux';

// Selector hook with shallowEqual comparison
function MyComponent() {
    // Using useSelector with shallowEqual to avoid unnecessary re-renders when the objects have the same values
    const myData = useSelector(state => state.myData, shallowEqual);
    // Component logic
}

This code demonstrates the use of the useSelector hook with the shallowEqual function from Redux. The shallowEqual function performs a shallow comparison between the current and next state, thereby preventing unnecessary re-renders if the selected state has not fundamentally changed, even if the object references have changed.

import React, { useCallback } from 'react';
import { useDispatch, useSelector } from 'react-redux';
import { updateValue } from './actions';

function MyComponent() {
    const dispatch = useDispatch();
    const value = useSelector(state => state.value);

    // Memoize the callback to maintain referential equality if dependencies haven't changed
    const memoizedCallback = useCallback(
        newValue => {
            dispatch(updateValue(newValue));
        },
        [dispatch]
    );

    // Component logic and UI rendering
}

In this code, we are using the useCallback hook to memoize a callback that dispatches an action. This ensures that the function reference remains the same across re-renders as long as the dispatch function does not change, thus avoiding unnecessary re-rendering of components that depend on this callback.

import React, { useMemo } from 'react';
import { useSelector } from 'react-redux';

function MyComponent() {
    const complexData = useSelector(state => state.complexData);

    // Memoize a computationally intensive calculation
    const computedValue = useMemo(() => computeExpensiveValue(complexData), [complexData]);

    // Component logic and UI rendering using computedValue
}

This code snippet showcases the usage of useMemo to memoize a computationally expensive calculation based on a piece of state. By passing complexData as a dependency, the calculation is only recomputed when complexData changes, thereby reducing unnecessary computations and re-renders.