---
title: "Switch between contour lines heights in meters and feet. | JavaScript maps SDK"
description: "Switch map contour line altitude units between meters and feet."
---
> 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.
# Switch between contour lines heights in meters and feet.
Change the units for the altitude of the contour lines, converting from meters to feet. For additional technical information, refer to the [Contours schema](https://docs.maptiler.com/schema/contours/) provided by MapTiler.
The Global Contours schema, created by MapTiler, contains contour lines for locations all around the globe in two widely used unit systems: meters and feet. With its global coverage, MapTiler’s contour lines can be utilized for various purposes, such as outdoor recreation planning, landscape analysis, and cartographic visualization.
### 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.OUTDOOR,
zoom: 13.42,
center: [-148.63567, 62.03381],
});
// switching contours units
const changeLayerSource = function(layer_id, source) {
// get layer definition, remove layer, add layer
const oldLayers = map.getStyle().layers;
const layerIndex = oldLayers.findIndex(l => l.id === layer_id);
const contourDef = oldLayers[layerIndex];
const before = oldLayers[layerIndex + 1] && oldLayers[layerIndex +1].id;
contourDef['source-layer'] = source;
map.removeLayer(layer_id);
map.addLayer(contourDef, before);
};
// switch units handler
const units = document.getElementById('units');
units.addEventListener('change', function() {
changeLayerSource('Contour', this.value);
changeLayerSource('Contour index', this.value);
changeLayerSource('Contour labels', this.value);
changeLayerSource('Glacier contour', this.value);
changeLayerSource('Glacier contour index', this.value);
changeLayerSource('Glacier contour labels', this.value);
});
```
#### index.html
```html
Switch between meters and feet
```
## Related examples
### [3D terrain map](https://docs.maptiler.com/sdk-js/examples/3d-map/)
Tutorials
Create and display 3D terrain maps on web pages.
### [Start with AR maps](https://docs.maptiler.com/sdk-js/examples/ar-control/)
Examples
Add an AR control button to map 3D viewports.
### [Add Contour Lines](https://docs.maptiler.com/sdk-js/examples/contour-lines/)
Examples
Add map contour lines generated from a raster-dem source.