heatmap.js is a JavaScript library for creating interactive heatmaps on web pages. It allows developers to visualize data density on a 2D canvas or map overlay, with customizable color gradients and opacity levels. The library is lightweight and easy to integrate into various web projects.

Pros

• Simple and intuitive API for creating heatmaps
• Supports both canvas-based and DOM-based rendering
• Highly customizable with various configuration options
• Works well with map overlays (e.g., Google Maps)

Cons

• Limited documentation and examples
• Not actively maintained (last update was in 2016)
• Lacks advanced features like animation or real-time updates
• May have performance issues with very large datasets

Code Examples

Creating a basic heatmap:

// Create a heatmap instance
var heatmapInstance = h337.create({
  container: document.querySelector('.heatmap'),
  radius: 40,
  maxOpacity: .8,
  minOpacity: 0
});

// Add data points
heatmapInstance.addData({
  x: 200,
  y: 100,
  value: 50
});

Customizing heatmap colors:

var heatmapInstance = h337.create({
  container: document.querySelector('.heatmap'),
  gradient: {
    '.5': 'blue',
    '.8': 'red',
    '.95': 'white'
  }
});

Using with Google Maps:

var map = new google.maps.Map(document.getElementById('map-canvas'));
var heatmap = new HeatmapOverlay(map, {
  radius: 20,
  maxOpacity: 0.8,
  scaleRadius: true,
  useLocalExtrema: true
});

heatmap.setData({
  max: 8,
  data: [{lat: 24.6408, lng:46.7728, count: 3}, ...]
});

Getting Started

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

   <script src="https://cdnjs.cloudflare.com/ajax/libs/heatmap.js/2.0.2/heatmap.min.js"></script>
   

2. Create a container element for the heatmap:

   <div class="heatmap" style="width: 100%; height: 400px;"></div>
   

3. Initialize the heatmap and add data:

   var heatmapInstance = h337.create({
     container: document.querySelector('.heatmap')
   });
   
   heatmapInstance.setData({
     max: 5,
     data: [
       {x: 10, y: 15, value: 5},
       {x: 50, y: 50, value: 2},
       // Add more data points as needed
     ]
   });
   

This will create a basic heatmap with default settings. You can customize the appearance and behavior by adjusting the configuration options when creating the heatmap instance.