How to Display High-Performance Vector Tiles from GeoJSON in Leaflet

In this tutorial, we’ll learn how to render large GeoJSON datasets on a Leaflet map using vector tiles generated dynamically via geojson-vt. This approach offers faster performance, smoother panning/zooming, and canvas rendering for complex layers.

✅ Why This Matters

Loading raw GeoJSON directly into Leaflet using L.geoJSON() can get painfully slow with thousands of features. geojson-vt chunks your data into canvas-rendered vector tiles — just like Mapbox or MapLibre do — but entirely client-side.

Think of it as slicing a pizza into tiles… Leaflet only loads the slice you're eating (viewing).

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Download Source Code: Click Here

Watch This Tutorial in Video: Click Here

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🧰 Prerequisites

• Basic HTML and JS knowledge

• GeoJSON data file

• Leaflet (v1.7+ recommended)

• jQuery (for document ready)

• Bootstrap (optional, for layout)

• geojson-vt library

• leaflet-geojson-vt plugin (custom) 

🗂️ Folder Structure

project/
│
├── index.html
├── data/
│   └── data.js            # Contains your GeoJSON as a JS variable
├── js/
│   ├── source_code.js     # Leaflet init + geojson-vt logic
│   └── leaflet-geojson-vt.js  # Plugin that draws vector tiles on canvas
├── lib/
│   └── leaflet/
│       ├── leaflet.js
│       ├── leaflet.css
│       ├── leaflet.ajax.min.js
│       └── jquery-3.5.1.js
└── lib/bootstrap/css/bootstrap.css

 

🔌 Step-by-Step Implementation

1. HTML Skeleton (index.html)

Loads Leaflet, Bootstrap, and JS files.

 

 

Key imports:

 

2. GeoJSON Source (data/data.js)

You must define a global data variable:

var data = {
  "type": "FeatureCollection",
  "features": [
    // your features here
  ]
};

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3. Vector Tile Plugin (leaflet-geojson-vt.js)

This custom plugin extends L.GridLayer and draws vector tiles using canvas.

Key logic:

createTile: function (coords) {
    const tile = L.DomUtil.create("canvas", "leaflet-tile");
    ...
    const features = this.tileIndex.getTile(coords.z, coords.x, coords.y)?.features || [];
    features.forEach(f => this.drawFeature(ctx, f));
    return tile;
}

4. Map Setup (js/source_code.js)

myMap = L.map('map_div', {
    center:[38.91454,-77.02171],
    zoom:12,
    zoomControl: false
});

lyrOSM = L.tileLayer('http://{s}.tile.osm.org/{z}/{x}/{y}.png').addTo(myMap);

var vtLayer = L.geoJson.vt(data, {
    maxZoom: 20,
    tolerance: 3,
    style: {
        fillColor: "#F2FF00",
        color: "#1EB300",
    }
}).addTo(myMap);

⚠️ Common Gotchas

• No geometry appears? Make sure your GeoJSON data variable is loaded before the script runs.

• Tile flickering or overlapping? Set canvas tile size consistently and manage CSS z-index.

• Too many features per tile? Adjust maxZoom, tolerance, and enable debug: 1 in options.

📈 Performance Tips

• Convert large shapefiles to GeoJSON offline before using.

• Use simplify-geojson or reduce feature count for better zoom responsiveness.

• Explore hybrid client-server approaches later with pg_tileserv or tilemaker.

💡 Next Enhancements

• Load GeoJSON from server via AJAX

• Add dynamic styling by feature properties

• Add legend and filter controls

• Use maplibre-gl for true vector rendering later

🔚 Conclusion

By using geojson-vt With Leaflet and a bit of canvas wizardry, you can render huge GeoJSON datasets on the fly — perfect for public dashboards, mobile-first maps, or offline-first apps.

Frequently Asked Questions

Q: What are Vector Tiles in Leaflet?

A: Vector tiles are small chunks of GeoJSON rendered as canvas tiles, allowing fast map performance in Leaflet even with large datasets.

Q: Why use geojson-vt instead of L.geoJSON?

A: geojson-vt converts GeoJSON to tiled format, enabling smooth zoom and pan without crashing the browser, unlike the basic L.geoJSON approach.

Q: Can I load GeoJSON from a URL instead of embedding it?

A: Yes, you can load external GeoJSON via AJAX and feed it to geojson-vt dynamically using Leaflet AJAX plugin.