Filter

Filter the map’s vector layers — GeoJSON files included — by their attributes. You author preset filters (a layer plus one or more attribute conditions) that end-users toggle on the map, and you decide whether they may also build their own filters, on the layers and fields you allow.

A filter keeps the features whose attribute is one of the chosen values; several conditions combine (a feature must match all of them). Filters change what the map shows — the data itself is never modified.

Parameters

Parameter	What it does
Preset filters	Named filters published with the map. Pick a layer, an attribute, then the values to keep — read straight from the layer’s data. Active by default applies a preset when the map loads (end-users can still turn it off).
End-users can build filters	Adds a small builder to the widget: end-users pick a layer, an attribute and the values to keep. Their filters stay local to their session — your presets never change.
Layers they may filter	The layers offered to the builder. None checked = every vector layer of the map.
Foldable button / Open by default	A button that unfolds the filter list, or an always-open panel (best in a sidebar).
Position	The map corner the widget lives in. The panel always unfolds toward the inside of the map.

What end-users see

A funnel button in the corner you picked, with a badge counting the active filters. It opens the list of your presets as switches; turning one on filters its layer immediately. If you allowed it, an Add a filter section lets them compose their own condition — layer, attribute, values — applied for the duration of their session and removable with one click.