> For the complete documentation index, see [llms.txt](https://docs.mapbox.com/mapbox-gl-js/ja/llms.txt)
# Check if Mapbox GL JS is supported
Use [`supported`](https://docs.mapbox.com/mapbox-gl-js/ja/api/properties/#supported) to check for Mapbox GL browser support, and show an alert if the browser does not support Mapbox GL. Find more information about browser support for Mapbox tools in the [Browser support](https://docs.mapbox.com/help/troubleshooting/mapbox-browser-support/) troubleshooting guide.
> Example code:
**JavaScript**
```html
Check if Mapbox GL JS is supported
```
**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(() => {
if (!mapboxgl.supported()) {
alert('Your browser does not support Mapbox GL');
} else {
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: mapContainerRef.current,
style: 'mapbox://styles/mapbox/standard',
center: [-74.5, 40],
zoom: 9
});
}
return () => mapRef.current.remove();
}, []);
return ;
};
export default MapboxExample;
```