Sending Data from a Child Component to a Parent Component in React

Learn how to effectively send data from a child component to a parent component in React. This guide breaks down the solution with easy-to-understand examples and best practices.
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This video is based on the question https://stackoverflow.com/q/73969250/ asked by the user 'Leo Messi' ( https://stackoverflow.com/u/9099077/ ) and on the answer https://stackoverflow.com/a/73969307/ provided by the user 'Jayce444' ( https://stackoverflow.com/u/5496808/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Sending Data from a Child Component to a Parent Component in React: A Step-by-Step Guide

React has become one of the most popular libraries for building user interfaces, but as developers dive into more complex applications, one common challenge arises: how to transfer data from a child component back to its parent component. This fundamental interaction is crucial for building dynamic web applications. In this guide, we’ll explore the problem and break down a solution step-by-step, using a practical example to illustrate the concepts.

The Problem

Imagine you have a React application with a parent component (App) and two child components, Inputs and List. The primary goal here is to send data (specifically, user input) from the Inputs child component back to the App parent component.

Initial Code Structure

Here is a simplified structure of our components:

[[See Video to Reveal this Text or Code Snippet]]

In this setup, we encounter two key issues:

The people array is declared as a regular variable, which resets on every render.

The callback function is not properly modifying the people array when adding new entries.

The Solution

To solve these issues, we need to make several changes:

Step 1: Manage State Properly

First, we should store people in a state variable rather than a simple variable. This ensures that the component retains its value across re-renders. Update your App component to:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Updating State Correctly

Instead of pushing new entries directly into the array (which mutates the state), use the state setter function to create a new array. Modify your callback function as follows:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Pass Functions as Props

In your Inputs component, the button's onClick handler should reference the function directly rather than calling it immediately. Change the button code to:

[[See Video to Reveal this Text or Code Snippet]]

Make sure you pass the necessary state and function from parent to child correctly. Now your Inputs.js file should look like this:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By handling state correctly and ensuring that our functions are passed as props in a functional way, we can successfully send data from a child component back to a parent component in React. This pattern of lifting state up and passing functions down is fundamental in React applications and lays the groundwork for effective component communication.

If you're struggling with similar issues or want to learn more about React and state management, be sure to experiment with the examples provided and see how these techniques can enhance your own applications!

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