Скачать или смотреть How to Dynamically Change the Classname of Buttons on Click in React Using an Array

Learn how to maintain a dynamic classname for clicked elements in React by managing state correctly with an array.
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This video is based on the question https://stackoverflow.com/q/69055455/ asked by the user 'Yash Sharma' ( https://stackoverflow.com/u/15952395/ ) and on the answer https://stackoverflow.com/a/69055587/ provided by the user 'CertainPerformance' ( https://stackoverflow.com/u/9515207/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Managing Classnames Dynamically in React

When working with dynamic content in a React application, it's common to have interactive elements that change their appearance based on user actions. If you've ever struggled with this feature, particularly regarding the className of buttons from a mapped array, you're not alone! This guide will guide you on how to create buttons that can change class upon clicking, allowing them to maintain that class until clicked again. Let's dive in!

The Problem: User Interaction and State Management

The scenario we are addressing involves a simple task list represented in an array called allTodos. Each item in this list can be clicked to toggle its visual state, indicated by a change in className. Here's what happens in our initial setup:

Clicking a button changes its class name from not_checked to checked.

However, clicking another button removes the checked class from the previously clicked button.

The objective is to keep a button 'checked' once clicked, and toggle it 'unchecked' when clicked again.

The Solution: Utilizing State Arrays for Tracking

To solve the problem effectively, we need to keep track of multiple checked states, instead of a single index that only tracks one button. This can be accomplished by implementing a stateful array. Let’s break down the solution into simple steps:

Step 1: Initial Setup

We start by creating an array for our todo items and importing any necessary dependencies from React:

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

Step 2: Implementing State with Checked Status

Instead of using a single index, we will create a new state that initializes the checked status for each todo item.

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

Step 3: Handling Button Clicks

Next, we'll create a function using a closure to allow toggling the checked state of each button. The handleClick function modifies the checked state of the specified todo.

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

Step 4: Rendering the Buttons

We map over the updated todos, rendering the buttons with conditional class names based on their checked status.

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

Step 5: Applying Styles

Lastly, you can define some basic CSS for the checked and not_checked classes to reflect visually when an item is active:

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

Conclusion

By structuring your state to accommodate multiple checks rather than a single index, you can easily manage the dynamic classes of your elements. This approach ensures that when you toggle items in your todo list, the desired functionality is achieved, making the UI much more interactive and intuitive.

Feel free to implement this method within your React application, and watch as your buttons maintain their class until toggled again! Happy coding!