API / Sources

TopoJSON

Load TopoJSON data, convert it to GeoJSON, and add it to the map as a GeoJSON source. Give the data with data or with url. If you give both, url is used.

The conversion uses the topojson-client package, which you must install. objectName selects the object to convert. If you do not set it, the component uses the first object in the topology.

Place layer components inside this component's children and they use this source automatically. The children render only after the data is converted. ondata receives the converted FeatureCollection, and onerror receives an error message if the fetch or conversion fails. The other props pass through to GeoJSON.

import { TopoJSON } from 'svelte-maplibre';

Props

data Topology

A TopoJSON Topology object. Mutually exclusive with url.
url string

URL to a TopoJSON file. Fetched and converted automatically. Mutually exclusive with data.
objectName string

Which named object to extract. Defaults to the first object key.
id string

Default: getId('topojson')

Source ID. Defaults to topojson-N.
generateId boolean

Default: false

Generate a unique id for each feature. This will overwrite existing IDs.
promoteId string

Use this property on the feature as the ID. This will overwrite existing IDs.
filter ExpressionSpecification
lineMetrics boolean

True to calculate line lengths. Required to use a line layer that uses the "line-gradient" paint property.
cluster ClusterOptions

Cluster configuration. Only applies to point-feature topologies — polygon/line geometries will silently ignore this option.
maxzoom number
attribution string
buffer number
tolerance number
ondata (fc: FeatureCollection) => void

Called with the converted FeatureCollection when data is ready.
onerror (message: string) => void

Called when fetch or conversion fails.
children Snippet

Source: src/lib/TopoJSON.svelte