Pass variable value from Geojson file to filter another Geojson layer Leaflet

Question

I have an leaflet map with 2 geojson file loaded locally using the leaflet ajax filter. I am trying to filter the second geojson (polyline) based on 'click' of any of the first geojson point feature. both of them had the same SiteID field I am able to get the feature ID,

           layer.on("click", function(e){ 
                 pollid= feature.properties.SiteID; // ID from first layer geojson


                 console.log(pollid);

                lyrSpider.addTo(map); // second geojson file 
                console.log(pollid);
            });

how can I pass the (pollid) to filter the second geojson

 function spiderfilter(feature) {


            if (feature.properties.SiteID == pollid) return true; // problem,
        }

I could not figure out the variable scope. here.

Answer 1

If you can create lyrSpider inside of the first function you showed, then you can set the filter option during creation like this:

layer.on("click", function(e){ 
    let pollid = feature.properties.SiteID;

    let lyrSpider = L.geoJSON(geoJSON_data, {
        filter: function(feature, layer) {
            if (pollid == feature.properties.SiteID) {
                return true;
            }
        }
    });

    lyrSpider.addTo(map);
});

See the L.geoJSON docs: http://leafletjs.com/reference-1.3.0.html#geojson-filter.