I might be misunderstanding you, but if you're talking about querying a service for feature JSON dynamically based on the current extent of the map, in [Esri Leaflet](http://esri.github.io/esri-leaflet/) we create a tile grid so that we can repeatedly pass identical queries when possible to leverage browser based caching.

You can see the relevant section of the open source Leaflet plugin API [here](https://github.com/Esri/esri-leaflet/blob/master/src/Layers/FeatureLayer/FeatureGrid.js)