> For the complete documentation index, see [llms.txt](https://docs.mapbox.com/mapbox-gl-js/llms.txt)
# Animate a point along a line
This example animates the position of a point by updating a GeoJSON source on each frame.
It first defines the animation as a GeoJSON object. Then it adds a [GeoJSON source](https://docs.mapbox.com/style-spec/reference/sources/#geojson) referring to that GeoJSON, and adds a [circle layer](https://docs.mapbox.com/style-spec/reference/layers/#circle) that uses that source.
Finally, it starts the animation with the JavaScript [`window.requestAnimationFrame()`](https://developer.mozilla.org/en-US/docs/Web/API/window/requestAnimationFrame) method to continuously update the GeoJSON object, resulting in a moving circle on the map.
> Example code:
**JavaScript**
```html
Animate a point along a line
```
**React**
```jsx
import React, { useEffect, useRef } from 'react';
import * as mapboxgl from 'mapbox-gl/esm';
import 'mapbox-gl/dist/mapbox-gl.css';
const MapboxExample = () => {
const mapContainerRef = useRef();
const mapRef = useRef();
useEffect(() => {
mapRef.current = new mapboxgl.Map({
// TO MAKE THE MAP APPEAR YOU MUST
// ADD YOUR ACCESS TOKEN FROM
// https://account.mapbox.com
accessToken: 'YOUR_MAPBOX_ACCESS_TOKEN',
container: 'map',
style: 'mapbox://styles/mapbox/standard',
center: [0, 0],
zoom: 2
});
const radius = 20;
function pointOnCircle(angle) {
return {
type: 'Point',
coordinates: [Math.cos(angle) * radius, Math.sin(angle) * radius]
};
}
mapRef.current.on('load', () => {
mapRef.current.addSource('point', {
type: 'geojson',
data: pointOnCircle(0)
});
mapRef.current.addLayer({
id: 'point',
source: 'point',
type: 'circle',
paint: {
'circle-radius': 10,
'circle-color': '#007cbf'
}
});
function animateMarker(timestamp) {
mapRef.current
.getSource('point')
.setData(pointOnCircle(timestamp / 1000));
requestAnimationFrame(animateMarker);
}
animateMarker(0);
});
}, []);
return ;
};
export default MapboxExample;
```