> For the complete documentation index, see [llms.txt](https://docs.mapbox.com/mapbox-gl-js/llms.txt)
# Filter symbols using a dynamic expression
This examples demonstrates a technique for filtering symbols on a map when the user toggles a checkbox.
This technique creates a [symbol](https://docs.mapbox.com/style-spec/reference/layers/#symbol) layer whose source includes several features with different `icon` properties. Expressions are used for filtering the layer to only show features whose `icon` property matches the selected checkboxes.
When a checkbox is toggled, [`setFilter`](https://docs.mapbox.com/mapbox-gl-js/api/map/#map#setfilter) is called to apply a dynamic filter expression based on the current state of the checkboxes.
An alternative technique using a multiple layers and `setLayoutProperty` to toggle their visibility is available at [Filter symbols by toggling a checkbox](https://docs.mapbox.com/mapbox-gl-js/example/filter-markers/)
> **Note: Referencing images in a style's sprite**
>
> This example uses the [Mapbox Light](https://www.mapbox.com/maps/light/) style. The `icon-image` used in this example comes from the Mapbox Light style's [sprite](https://docs.mapbox.com/help/glossary/sprite/).
>
> To view all available images in a style's sprite or add additional images, open the style in [Mapbox Studio](https://studio.mapbox.com/styles/) and click the **Images** tab. To add a new image to the style at runtime see the [Add an icon to the map](https://docs.mapbox.com/mapbox-gl-js/mapbox-gl-js/example/add-image/) example.
> Example code:
**JavaScript**
```html
Filter symbols using a dynamic expression
```