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Javascript – How to correctly manage state in a parent component when passing data to child components in React?

I’m building a React application where I have a parent component that holds the state and several child components that need to receive and update this state. I’m using props to pass the state and a callback function to update the state from the child components. However, I’m encountering issues where the state updates aren’t reflecting immediately in the child components, or the state becomes inconsistent.

function ParentComponent() {
    const [data, setData] = useState([]);

    const updateData = (newData) => {
        setData(newData);
    };

    return (
        <div>
            <ChildComponent data={data} updateData={updateData} />
            <AnotherChildComponent data={data} />
        </div>
    );
}

function ChildComponent({ data, updateData }) {
    const handleClick = () => {
        const updatedData = [...data, 'New Item'];
        updateData(updatedData);
    };

    return (
        <div>
            <button onClick={handleClick}>Add Item</button>
        </div>
    );
}

function AnotherChildComponent({ data }) {
    return (
        <ul>
            {data.map((item, index) => (
                <li key={index}>{item}</li>
            ))}
        </ul>
    );
}

What is the best practice for managing state between parent and child components in React?
How can I ensure that all child components receive the updated state immediately?
Are there any performance concerns with this approach, and how can I optimize it?

Tags:

2

Answers


  1. 0

    These are best practices that you can consider:

    Use Functional Updates with useState

    Use the call function in setState. This ensures that you are working with the latest state.

    Ensure State Immutability

    Always ensure the state is immutable while updating the state. In your example, you’re already using the spread operator (…) to create a new array when adding items, which is good.

    Avoid Unnecessary Re-Renders using useCallback , useMemo

    Passing new references to props can cause unnecessary re-renders. In your case, every time the updateData function is called, it creates a new array, which is fine because you want the state to update.
    However, ensure that the child components do not perform expensive operations when they are in use. Effect hooks or other lifecycle methods unless the state or props genuinely change.

    Memoization

    If you notice performance issues due to frequent re-renders, consider using React.memo to memoize the child components. This prevents them from re-rendering unless their props change.

    import React, { useState, useCallback } from 'react';

function ParentComponent() {
    const [data, setData] = useState([]);

    const updateData = useCallback((newData) => {
        setData((prevData) => [...prevData, newData]);
    }, []);

    return (
        <div>
            <ChildComponent data={data} updateData={updateData} />
            <AnotherChildComponent data={data} />
        </div>
    );
}

const ChildComponent = React.memo(({ data, updateData }) => {
    const handleClick = () => {
        updateData('New Item');
    };

    return (
        <div>
            <button onClick={handleClick}>Add Item</button>
        </div>
    );
});

const AnotherChildComponent = React.memo(({ data }) => {
    return (
        <ul>
            {data.map((item, index) => (
                <li key={index}>{item}</li>
            ))}
        </ul>
    );
});

export default ParentComponent;
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  2. 0

    Modify your updateData function to receive only an added item and use prevState in setData

    const updateData = (newItem) => {setData((prevState) => [...prevState, newItem]);};

    In the child component pass only the new item that you want to add

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