How to access a DOM element in React? What is the equilvalent of document.getElementById() in React

How to Access a DOM Element in React

If you're working with React, you might be wondering how to access a DOM element like you would using document.getElementById() in vanilla JavaScript. In React, the equivalent method to access a DOM element is by using Refs.

Refs in React provide a way to access DOM element or a React component instance created in the render method. Refs are commonly used to interact with third-party libraries or to achieve focus on a certain element.

Common Issue: Selecting DOM Elements in React

In the given code snippet, the error TypeError: document.getElementById(...) is null occurs when trying to access the DOM element with the ID fetched from the state using document.getElementById(this.state.baction). This approach doesn't work in React because the element hasn't been created yet and cannot be accessed using the traditional DOM API.

Easy Solution: Using Refs in React

To access a DOM element in React, you can use the ref attribute. Refs allow your React components to refer to DOM nodes or other React components. They can be assigned to a class component instance or a function component using the useRef() hook.

In your case, let's update the App component to include refs for each Progressbar:

var App = React.createClass({
    // ...

    // Create refs for the Progressbar elements
    progress1Ref: React.createRef(),
    progress2Ref: React.createRef(),
    progress3Ref: React.createRef(),

    // ...

    handleClick10: function (e) {
        console.log('You clicked: ', this.state.baction);
        
        // Access the ref of the selected progress bar
        const selectedProgressBar = this.state.baction === 'Progress1' ? this.progress1Ref.current :
                                    this.state.baction === 'Progress2' ? this.progress2Ref.current :
                                    this.progress3Ref.current;

        // Perform the operation
        selectedProgressBar.addPrecent(10);
    },

    render: function () {
        return (
            <div className="center">Progress Bars Demo
                <Progressbar completed={25} id="Progress1" ref={this.progress1Ref} />
                <h2 className="center"></h2>
                <Progressbar completed={50} id="Progress2" ref={this.progress2Ref} />
                <h2 className="center"></h2>
                <Progressbar completed={75} id="Progress3" ref={this.progress3Ref} />
                <h2 className="center"></h2>
                {/* Rest of the code */}
            </div>
        )
    }
});

Here's what you need to do:

1. Import the useRef() hook from the react package.

2. Create a ref for each Progressbar element using React.createRef().

3. Assign the ref to the corresponding Progressbar element using the ref attribute.

4. In the handleClick10 function, retrieve the ref of the selected progress bar based on the value of this.state.baction.

5. Use the ref to perform the desired operation (addPrecent(10) in this case).

By using refs, you can now access and interact with specific DOM elements inside your React components.

Conclusion

In React, accessing DOM elements is done using Refs instead of traditional DOM methods like document.getElementById(). By creating and assigning refs to the desired elements, you can easily interact with them in your React components. Remember to use ref.current to access the actual DOM element when needed.

Now that you know how to access DOM elements in React, go ahead and try it out in your own projects. Happy coding! 😄

Have you ever faced trouble accessing DOM elements in React? Share your experience in the comments below!