Group features from feature layer by specific field without making multiple queries

Question

I have a feature layer where one of the properties always takes 4 possible values.

Now I want to make 1 request to get all the features, group them by this property and feed each group to a different markercluster (or esri leaflet cluster) so I can have a separate cluster for every group. However it doesn't seem possible to do it without creating a cluster layer for each group explicitly, which would result in 4 separate requests and multiplying complexity. As far as I can see pointToLayer and iconCreateFunction doesn't really do the job (and they do weird things when points are removed or recreated), and panes only group the rendered markers, not the actual cluster itself.

Answer 1

marker.cluster clusters need names, you would have to declare each one separately.
You can however query your full layer once hold the GeoJSON object under the name data and use leaflet's filter method

var data;
fetch('url://of.the.esri.featureserver.query', {
  method: 'GET'
}).then(function(response) {
  data = response.json();
})

var cluster1 = L.markerClusterGroup();  
var cluster2 = L.markerClusterGroup();  

var layer1 = L.geoJSON(data, {
  filter: function(feature){
    if(feature.properties.column == 1 ){
        return true
      }
}
});

var layer2 = L.geoJSON(data, {
  filter: function(feature){
    if(feature.properties.column == 2 ){
        return true
      }
}
});

layer1.addTo(cluster1);
layer2.addTo(cluster2);

This way you get the data once, and use it multiple times.