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Discover how to effectively `lift state` from child to parent components in React to retrieve values, complete with practical examples.
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This video is based on the question https://stackoverflow.com/q/70098755/ asked by the user 'Тахир Мухаметов' ( https://stackoverflow.com/u/17120111/ ) and on the answer https://stackoverflow.com/a/70100056/ provided by the user 'Khabir' ( https://stackoverflow.com/u/7119904/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Get the Value from a Child Component in React

In React, managing data between components can sometimes feel like a daunting task. A common scenario developers face is needing to extract a value from a child component to a parent component. This can be particularly relevant when dealing with forms or interactive elements. In this guide, we will explore how to effectively lift state from a child component back up to its parent, enabling seamless data flow in your React applications.

Understanding the Problem

Imagine you have a simple child component, CodeVerify, that allows users to input a verification code. However, you also want to capture this code in the parent component where CodeVerify is rendered. This situation is a classic example of needing to lift state, which enables better communication between components in React.

Here's the basic structure of our child component:

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

Now, let’s walk through how to effectively retrieve the value from CodeVerify in its parent.

The Solution: Lifting State Up

To capture the value input by the user in the CodeVerify component, we need to lift its state up to the parent component. In other words, we will manage the state in the parent and pass down a function to allow the child to update that state.

Step 1: Create the Parent Component

The parent component will maintain the state and define a function that sets this state. Below is an example of how to implement this:

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

Step 2: Modify the Child Component

Next, we will modify the CodeVerify component to accept the onCodeChange function through its props and invoke this function whenever the user changes the input value.

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

Important Points to Note

Props for Communication: We define the function handleCodeChange in the parent component, which gets passed to CodeVerify as a prop. This prop acts as a bridge for transferring data from the child back to the parent.

Event Handling: Within CodeVerify, we set up an event handler handleChange that both updates the child's local state and calls the parent's function to update its state.

State Synchronization: With this setup, any changes made in CodeVerify will automatically update the verificationCode state in the ParentComponent, providing real-time data flow.

Conclusion

By lifting state from your child component to its parent, you create a more intuitive data flow in your React applications. This method is not only effective but also encourages better management of state across components, leading to cleaner and more maintainable code.

With these techniques at your disposal, you should feel empowered to tackle the common challenges associated with component communication in React. Happy coding!