stats.js is a lightweight JavaScript performance monitor that provides real-time statistics for web applications. It displays frames per second (FPS), milliseconds per frame (MS), and memory usage in a small, customizable panel that can be easily integrated into any web project.

Pros

• Simple and easy to use with minimal setup required
• Lightweight and performant, with negligible impact on application performance
• Customizable appearance and positioning
• Supports multiple panels for monitoring different metrics simultaneously

Cons

• Limited to basic performance metrics (FPS, MS, MB)
• May not provide enough detail for complex performance analysis
• Requires manual integration into each project (no automatic instrumentation)
• Not actively maintained (last update was in 2020)

Code Examples

1. Basic usage:

// Create a new Stats instance
const stats = new Stats();

// Add the stats panel to the document
document.body.appendChild(stats.dom);

// Update stats in the animation loop
function animate() {
    stats.begin();
    // Your animation code here
    stats.end();
    requestAnimationFrame(animate);
}
animate();

2. Using multiple panels:

const stats = new Stats();
stats.showPanel(0); // 0: fps, 1: ms, 2: mb, 3+: custom
document.body.appendChild(stats.dom);

const stats2 = new Stats();
stats2.showPanel(1);
stats2.dom.style.cssText = 'position:absolute;top:0;left:80px;';
document.body.appendChild(stats2.dom);

3. Custom panel:

const stats = new Stats();
stats.showPanel(3); // Custom panel
stats.dom.style.cssText = 'position:absolute;top:0;left:0;';
document.body.appendChild(stats.dom);

const myPanel = stats.addPanel(new Stats.Panel('Custom', '#ff8', '#221'));
const update = () => {
    myPanel.update(Math.random() * 100, 100);
    requestAnimationFrame(update);
};
update();

Getting Started

1. Include the stats.js library in your HTML:

   <script src="https://cdnjs.cloudflare.com/ajax/libs/stats.js/r17/Stats.min.js"></script>
   

2. Create a new Stats instance and add it to your document:

   const stats = new Stats();
   document.body.appendChild(stats.dom);
   

3. Update the stats in your animation loop:

   function animate() {
       stats.begin();
       // Your animation code here
       stats.end();
       requestAnimationFrame(animate);
   }
   animate();