---
title: "Use a fallback image | JavaScript maps SDK"
description: "Use a coalesce expression to display a fallback image."
---
> For AI agents: a documentation index is available at [/llms.txt](https://docs.maptiler.com/llms.txt). Markdown versions of all pages are available by appending .md to any URL.
# Use a fallback image
Use a [`coalesce`](https://docs.maptiler.com/gl-style-specification/expressions/#coalesce) expression to display another image when a requested image is not available.
### NPM module setup
```bash
npm install --save @maptiler/sdk
```
#### main.js
```js
import { Map, MapStyle, config } from '@maptiler/sdk';
import '@maptiler/sdk/dist/maptiler-sdk.css';
config.apiKey = 'YOUR_MAPTILER_API_KEY_HERE';
const map = new Map({
container: 'map',
style: MapStyle.STREETS,
center: [-77, 38.75],
zoom: 5
});
map.on('load', function () {
map.addSource('points', {
'type': 'geojson',
'data': {
'type': 'FeatureCollection',
'features': [
{
'type': 'Feature',
'geometry': {
'type': 'Point',
'coordinates': [
-77.03238901390978,
38.913188059745586
]
},
'properties': {
'title': 'Washington DC',
'icon': 'monument'
}
},
{
'type': 'Feature',
'geometry': {
'type': 'Point',
'coordinates': [-79.9959, 40.4406]
},
'properties': {
'title': 'Pittsburgh',
'icon': 'bridges'
}
},
{
'type': 'Feature',
'geometry': {
'type': 'Point',
'coordinates': [-76.2859, 36.8508]
},
'properties': {
'title': 'Norfolk',
'icon': 'harbor'
}
}
]
}
});
map.addLayer({
'id': 'points',
'type': 'symbol',
'source': 'points',
'layout': {
'icon-image': [
'coalesce',
['image', ['concat', ['get', 'icon'], '-15']],
['image', 'zoo']
],
'text-field': ['get', 'title'],
'text-font': ['Open Sans Semibold', 'Arial Unicode MS Bold'],
'text-offset': [0, 0.6],
'text-anchor': 'top'
}
});
});
```
#### index.html
```html
Use a fallback image | NPM example
```
#### style.css
```css
body {margin: 0; padding: 0;}
#map {position: absolute; top: 0; bottom: 0; width: 100%;}
```
### Basic JavaScript setup
```html
Use a fallback image
```
## Related examples
### [Icon image URL inside a rich text format label](https://docs.maptiler.com/sdk-js/examples/rich-text-format/)
Examples
Display rich text labels with texts and icons.
### [Filter symbols by text input](https://docs.maptiler.com/sdk-js/examples/filter-markers-by-input/)
Examples
Filter symbols by typing names into a text input.
### [Use locally generated ideographs](https://docs.maptiler.com/sdk-js/examples/local-ideographs/)
Examples
Use the localIdeographFontFamily setting to speed up map load times by using locally available fonts instead of font data fetched from the server.
### [Variable label placement](https://docs.maptiler.com/sdk-js/examples/variable-label-placement/)
Examples
Dynamically shift label positions to keep them visible.