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# clusteringIdentifier

An identifier for grouping annotations into the same cluster.

```
get clusteringIdentifier(): string | null;
set clusteringIdentifier(value: string | null);
```

## Discussion

For MapKit JS to cluster annotations, an annotation needs a `clusteringIdentifie`r. When annotations collide and have the same `clusteringIdentifier`, MapKit JS clusters them together.

The default value is `null`.

For more details, see [Clustering annotations](/documentation/MapKitJS/clustering-annotations).

---

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