Draw a Circle
Maps JS does not have a native circle geometry type for geographic radii, so circles are drawn by generating a GeoJSON polygon with many sides that approximates a circle at the correct radius in meters. Turf.js provides a circle helper that handles the geodesic math. Use this technique to draw coverage areas, proximity zones, search radii, or any geographic region defined by a center point and distance.
const API_KEY = 'YOUR_API_KEY';
function createGeodesicCircle(center, radiusKm, steps = 64) {
const coords = [];
for (let i = 0; i <= steps; i++) {
const angle = (i / steps) * 2 * Math.PI;
const dx = radiusKm / 111.32;
const dy = radiusKm / (111.32 * Math.cos(center[1] * Math.PI / 180));
coords.push([center[0] + dy * Math.sin(angle), center[1] + dx * Math.cos(angle)]);
}
return { type: 'Feature', geometry: { type: 'Polygon', coordinates: [coords] } };
}
const map = new maptoolkit.Map({
container: 'map',
apiKey: API_KEY,
style: `https://styles.maptoolkit.net/maptoolkit/maptoolkit.summer.json?api_key=${API_KEY}`,
center: [11.39085, 47.27574],
zoom: 11,
attributionControl: { compact: false }
});
map.addControl(new maptoolkit.NavigationControl(), 'top-right');
map.on('load', () => {
const circle = createGeodesicCircle([11.39085, 47.27574], 5);
map.addSource('circle', { type: 'geojson', data: circle });
map.addLayer({
id: 'circle-fill',
type: 'fill',
source: 'circle',
paint: { 'fill-color': '#3887be', 'fill-opacity': 0.3 }
});
map.addLayer({
id: 'circle-outline',
type: 'line',
source: 'circle',
paint: { 'line-color': '#3887be', 'line-width': 2 }
});
});<!DOCTYPE html>
<html lang="en">
<head>
<title>Draw a Circle - Maptoolkit Maps JS</title>
<meta property="og:description" content="Draw a geographic circle using a GeoJSON polygon approximation." />
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<script src="https://unpkg.com/@maptoolkit/[email protected]/dist/maptoolkit.js"></script>
<link rel="stylesheet" href="https://unpkg.com/@maptoolkit/[email protected]/dist/maptoolkit.css" />
<style>
html, body { width: 100%; height: 100%; margin: 0; padding: 0; }
#map { width: 100%; height: 100%; }
</style>
</head>
<body>
<div id="map"></div>
<script>
const API_KEY = 'YOUR_API_KEY';
function createGeodesicCircle(center, radiusKm, steps = 64) {
const coords = [];
for (let i = 0; i <= steps; i++) {
const angle = (i / steps) * 2 * Math.PI;
const dx = radiusKm / 111.32;
const dy = radiusKm / (111.32 * Math.cos(center[1] * Math.PI / 180));
coords.push([center[0] + dy * Math.sin(angle), center[1] + dx * Math.cos(angle)]);
}
return { type: 'Feature', geometry: { type: 'Polygon', coordinates: [coords] } };
}
const map = new maptoolkit.Map({
container: 'map',
apiKey: API_KEY,
style: `https://styles.maptoolkit.net/maptoolkit/maptoolkit.summer.json?api_key=${API_KEY}`,
center: [11.39085, 47.27574],
zoom: 11,
attributionControl: { compact: false }
});
map.addControl(new maptoolkit.NavigationControl(), 'top-right');
map.on('load', () => {
const circle = createGeodesicCircle([11.39085, 47.27574], 5);
map.addSource('circle', { type: 'geojson', data: circle });
map.addLayer({
id: 'circle-fill',
type: 'fill',
source: 'circle',
paint: { 'fill-color': '#3887be', 'fill-opacity': 0.3 }
});
map.addLayer({
id: 'circle-outline',
type: 'line',
source: 'circle',
paint: { 'line-color': '#3887be', 'line-width': 2 }
});
});
</script>
</body>
</html>Use the prompt below with any LLM to get the same result. Make sure the Maptoolkit MCP server is connected first — check out AI Integration & MCP to get started.
Use the Maptoolkit Connector. Create an interactive map with zoom level 11, centered around [11.39085, 47.27574]. Draw a geographic circle with a 5 km radius at the center.