How to Render Elements using onFocus and onBlur in React JS

React JS provides powerful event handling capabilities that allow you to create interactive user interfaces. In this tutorial, we will explore how to use the onFocus and onBlur events in React to render elements dynamically based on user interactions.

Explaining onFocus and onBlur in React

When building web applications with React, it’s essential to understand how to handle user interactions effectively. Two commonly used events for managing focus in React are onFocus and onBlur.

The onFocus event occurs when an element receives focus, typically when a user clicks on it or navigates to it using the keyboard. Conversely, the onBlur event is triggered when the element loses focus, such as when the user clicks outside the element or tabs to another part of the page.

These events are valuable for creating dynamic user experiences, such as displaying additional information or validation messages when input fields are focused or blurred.

How to Create the Issue

To illustrate how onFocus and onBlur events can lead to unexpected behavior, let’s consider a scenario where we have an input field that should display additional information when focused but hide it when blurred.

import React, { useState } from 'react';

const IssueExample = () => {
  const [showInfo, setShowInfo] = useState(false);

  return (
    <div>
      <input
        onFocus={() => setShowInfo(true)}
        onBlur={() => setShowInfo(false)}
        placeholder="Enter your text"
      />
      {showInfo && <div>Additional information</div>}
    </div>
  );
};

export default IssueExample;

Understanding the Root Cause of the Issue

The root cause of the issue lies in the way onFocus and onBlur events are handled in React. When the input field loses focus, the onBlur event is triggered, causing the additional information to be hidden immediately. However, this behavior may not always align with the user’s intentions, especially if they intend to interact with the additional content.

Step-by-Step Solution

Step 1: Separate the Additional Information Component

To resolve this issue, we can separate the additional information into its own component.

const AdditionalInfo = () => {
  return <div>Additional information</div>;
};

Step 2: Use State to Control Visibility

const [isFocused, setIsFocused] = useState(false);

Step 3: Update onFocus and onBlur Handlers

<input
  onFocus={() => setIsFocused(true)}
  onBlur={() => setIsFocused(false)}
/>

Step 4: Render Additional Information Based on State

{isFocused && <AdditionalInfo />}

Step 5: Test and Refine

Make sure to thoroughly test the updated behavior to ensure it aligns with user expectations.

Complete React JS Example Code

Below is the complete example code demonstrating how to render elements using onFocus and onBlur events in React:

import React, { useState } from 'react';

const AdditionalInfo = () => {
  return <div>Additional information</div>;
};

const FocusBlurExample = () => {
  const [isFocused, setIsFocused] = useState(false);

  return (
    <div>
      <input
        onFocus={() => setIsFocused(true)}
        onBlur={() => setIsFocused(false)}
        placeholder="Enter your text"
      />
      {isFocused && <AdditionalInfo />}
    </div>
  );
};

export default FocusBlurExample;

This example illustrates how to use onFocus and onBlur events to dynamically render elements in a React component based on user interaction.