getFeatureKey

Resolves a feature key from a GeoJSON feature

Use it when you need a stable identifier for rendering or DOM targeting

Parameters

Parameter	Type	Default	Description
feature	MapFeatureData	—	Feature to inspect
idKey?	string	'id'	Key checked on the feature and then on feature.properties
fallback?	string | number	—	Optional fallback value returned when no key is found

Behavior

Checks in order:

1. feature[idKey]
2. feature.properties?.[idKey]
3. fallback

If no value is found and no fallback is provided, it returns undefined

Usage

const key = getFeatureKey(feature)
const keyedBySlug = getFeatureKey(feature, 'slug')
const keyedWithFallback = getFeatureKey(feature, 'id', index)

See feature API