js-marker-clusterer

The library creates and manages per-zoom-level clusters for large amounts of markers. Google API v3.

https://cdnjs.webstatic.cn/ajax/libs/js-marker-clusterer/1.0.0/markerclusterer.js
https://cdnjs.webstatic.cn/ajax/libs/js-marker-clusterer/1.0.0/markerclusterer_compiled.js