How to Implement a Progress Bar

[juna962]

How to Implement a Progress Bar

Problem Statement

When implementing a progress bar that tracks an action triggered by a button click, the current implementation causes the entire page to refresh continuously while fetching progress updates from the database. This is inefficient and creates a poor user experience.

The current flow:

1. Action is triggered by button click
2. Total execution time is pre-calculated
3. Progress value is written to database
4. Progress bar updates by querying the database
5. Page refreshes to show updated progress

Solutions

1. AJAX-Based Updates

Use AJAX to fetch progress updates without refreshing the page:

function updateProgressBar() {
    $.ajax({
        url: '/get-progress',
        method: 'GET',
        success: function(response) {
            $('#progress-bar').css('width', response.progress + '%');
            $('#progress-bar').text(response.progress + '%');
        },
        error: function(error) {
            console.error('Error fetching progress:', error);
        }
    });
}

// Update progress every second
setInterval(updateProgressBar, 1000);

2. WebSocket Implementation

Use WebSockets for real-time progress updates:

1. Set up a WebSocket connection from the server to push updates
2. Listen for updates on the frontend
3. Update the progress bar when new data arrives

This approach provides real-time updates without polling.

3. Modern Framework Implementation (React Example)

import React, { useState, useEffect } from 'react';

function ProgressBar() {
    const [progress, setProgress] = useState(0);

    useEffect(() => {
        const interval = setInterval(() => {
            fetch('/get-progress')
                .then(response => response.json())
                .then(data => setProgress(data.progress))
                .catch(console.error);
        }, 1000);

        // Cleanup on unmount
        return () => clearInterval(interval);
    }, []);

    return (
        <div className="progress-bar-container">
            <div
                className="progress-bar"
                style={{ width: `${progress}%` }}
            >
                {progress}%
            </div>
        </div>
    );
}

export default ProgressBar;

4. Backend Optimization Tips

1. Use efficient database queries

   • Consider caching progress values
   • Implement proper indexing
   • Use lightweight response formats

2. Implement proper error handling

   • Handle timeouts gracefully
   • Provide fallback mechanisms
   • Log errors for debugging

3. Consider rate limiting

   • Prevent excessive database queries
   • Implement appropriate update intervals
   • Use connection pooling

Best Practices

1. Error Handling: Always implement proper error handling for failed requests or interrupted connections.

2. Cleanup: Remember to clear intervals and close connections when components unmount or operations complete.

3. User Experience:

   • Show meaningful progress messages
   • Implement a smooth animation
   • Provide fallback UI for failed states

4. Performance:

   • Use appropriate update intervals
   • Implement request debouncing
   • Cache results when possible

Implementation Considerations

When choosing an approach, consider:

• Real-time requirements
• Server capabilities
• Framework constraints
• Browser compatibility
• Performance requirements