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A custom graphics layer that inherits from ArcGIS js graphics layer. Clustering is nothing special but I couldn't find an arcgis js api layer that clustered with flares which is why I created this.

The clustering is performed using a grid system based on the current extent, the pixel dimensions of the map and a configurable cluster ratio that can be set to suit a data set.

Support for both for 3.x and 4.x.

Note: The latest version will work with arcgis-js-api version v4.16. Check out the branches to find support for older api versions.


  • Flares will be created for individual points when the cluster contains <= a configured amount of points. Selecting these clusters will open an info window for the object.

  • Flares can also be created for counts of sub types. For example, if all of your data objects contain a property called 'Type', you can create flares for large clusters that contain the count of each unique value of the property 'Type'.

  • The boundary of the points in a cluster can also be displayed as a polygon behind the flare with a separate renderer to style however you like. They can be displayed on hover, tap, all the time or not at all.

  • Summary flares with the text '...' and a tooltip containing all data will be created if there's too many to fit in the configured total amount of flares to display.

  • Configure the symbology to be whatever you want by using a renderer for the clusters and single symbols and an optional second renderer for the cluster boundaries.

  • Supports MapView (2d) and SceneView (3d) for api v4.x.

All of the options are explained in the constructor of the layer so just check out the code for a full explanation. Demos are here:

v3.x -

v4.x -


If you want to run it locally just download or clone the repo and run

npm install


npm start

The reload server will spin up an instance on localhost:8080. v4.x will be compiled from typescript.

There's no npm package yet so if you want to add it to your project there's two options.

  • Grab the ts file typescript/FlareClusterLayer_v4.ts and place it somewhere in your project so it will be compiled along with the rest of your project. You'll also need @types/arcgis-js-api and the dojo typings included.

  • Grab the already compiled fcl/FlareClusterLayer_v4.js and reference it like the other javascript esri amd modules. An example of doing this is in the index_v4.html page.

api v4.x notes

Moved all of the animations out of the code and added css classes to elements instead. Animations can be performed using css instead of in code. This allows for much more flexibility. Example css that replicates/extends the v3.x animations are in the index_v4.html example.

There's no @types package for dojo v11.x, but there is an npm package 'dojo-typings'. Even the dojo-typings package doesn't go as high as 1.12.x which arcgis now uses. Had to just include a reference to the dojo types in a custom index.d.ts file.

If you plan to include the typescript/FlareClusterLayer_v4.ts file in your project you may need to change the import statements at the top of the file depending on the module loader and typescript compilation options you're using.

You would probably also need to remove the reference to the index.d.ts from typings at the top of the file, and just include the required typings file however your project already manages this.

Cross browser notes on the example CSS animations:

  • IE/Edge: These POS's don't support transforms on svg elements using css, so the css transform animations won't work.

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