Popups bound to instances of FeatureGroup are discarded when extracting points from layers.

[Sam152]

• I'm reporting a bug, not asking for help
• I'm sure this is a Leaflet.MarkerCluster code issue, not an issue with my own code nor with the framework I'm using (Cordova, Ionic, Angular, React…)
• I've searched through the issues to make sure it's not yet reported

---

How to reproduce

• Leaflet version I'm using: latest stable

• Leaflet.MarkerCluster version I'm using: latest tagged

• Browser (with version) I'm using: all browsers

• OS/Platform (with version) I'm using: OSX

• Create a LayerGroup, add some items to it.

• Bind a popup to the layer group.

• Add the layer group to a cluster and add the cluster to a map.

• Any popup bound to the LayerGroup is discarded when non-group layers are extracted in addLayers.

What behaviour I'm expecting and which behaviour I'm seeing

It would be good if things bound to the group are transferred to child layers as they are extracted. I have only reproduced this with a popup but I imagine the same might apply to events and other methods.

Minimal example reproducing the issue

• this example is as simple as possible
• this example does not rely on any third party code

Here is a simple way to reproduce the issue:

https://plnkr.co/edit/lbtWnmaBILmvrWYB8ARp

[ghybs]

As you noticed, unfortunately a MarkerClusterGroup does not keep track of the Layer Groups.

However a simple workaround is to use your Group eachLayer method to assign the popup individually to each child layer.

[Sam152]

What do you think to the approach in #971?