Implementing Drag and Drop Functionality with useRef

Implementing drag-and-drop functionality using React's useRef hook involves creating a reference to the draggable element and handling drag events. The useRef hook allows us to access and manipulate DOM elements directly in React functional components. By using useRef, we can track the position and behaviour of the dragged element during drag-and-drop interactions efficiently.

Output Preview:

Prerequisites:

• Node & NPM
• React JS
• ReactJS Hooks

Steps to Setup the Application:

Step 1: Create a reactJS application by using this command

npx create-react-app drag-and-drop-app

Step 2: Navigate to project directory

cd drag-and-drop-app

Folder Structure:

Approach to create Drag & Drop Functionality with useRef :

• First define CSS styles for the drag-and-drop container and draggable items using classes like .drag-and-drop and .drag-item.
• Use useRef in the React component to create a reference to the draggable item (dragItemRef in this example).
• Implement handleDragStart function to set data during drag start and update the dragItemRef with the dragged element.
• Create handleDragOver function to prevent default behavior, calculate new position based on mouse coordinates, and update the dragged element's position accordingly.
• Render the drag-and-drop container and draggable item components in your main App component (App.js) and handle drag events accordingly.

Example: Illustration to design drag and drop functionality using useref.

CSS

/* DragAndDrop.css */

.drag-and-drop {
    width: 100vw;
    height: 100vh;
    background-color: #f0f0f0;
}

h1 {
    text-align: center;
}

.drag-item {
    width: 100px;
    height: 50px;
    background-color: #ccc;
    border: 2px solid #666;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 16px;
    cursor: move;
    position: absolute;
}

JavaScript

// DragAndDrop.js

import React, { useRef } from 'react';
import './DragAndDrop.css';

const DragAndDrop = () => {
    const dragItemRef = useRef(null);

    const handleDragStart = (e) => {
        const target = e.target;
        e.dataTransfer.setData('text/plain', '');
        dragItemRef.current = target;
    };

    const handleDragOver = (e) => {
        e.preventDefault();
        const target = dragItemRef.current;
        if (!target) return;

        const x = e.clientX - target.offsetWidth / 2;
        const y = e.clientY - target.offsetHeight / 2;
        target.style.left = x + 'px';
        target.style.top = y + 'px';
    };

    return (
        <div
            className="drag-and-drop"
            onDragOver={handleDragOver}>
            <div
                className="drag-item"
                draggable="true"
                onDragStart={handleDragStart}>
                Drag me
            </div>
        </div>
    );
};

export default DragAndDrop;

JavaScript

// App.js

import React from 'react';
import DragAndDrop from './DragAndDrop';

const App = () => {
    return (
        <div>
            <h1>Drag and Drop Example</h1>
            <DragAndDrop />
        </div>
    );
};

export default App;

JavaScript

// index.js

import React from 'react';
import ReactDOM from 'react-dom';
import App from './App';

ReactDOM.render(
  <React.StrictMode>
    <App />
  </React.StrictMode>,
  document.getElementById('root')
);

Step to Run Application: Run the application using the following command from the root directory of the project.

npm start

Output: Your project will be shown in the URL http://localhost:3000/