How to remove all active layers or to know all active layers in leaflet?

[nmccready]

From @princeshahnawaz2012 on February 17, 2015 10:18

I just need to know if there is any function which helps to return all active layers. basically, I need this function to remove all layers due to my ajax call. Here is my main function ...

function initialize(){
// set up the map var map = L.map('map').setView([51.505, -0.09], 13);

    L.tileLayer('https://{s}.tiles.mapbox.com/v3/{id}/{z}/{x}/{y}.png', {
        maxZoom: 18,
        attribution: 'Map data &copy; <a href="http://openstreetmap.org">OpenStreetMap</a> contributors, ' +
            '<a href="http://creativecommons.org/licenses/by-sa/2.0/">CC-BY-SA</a>, ' +
            'Imagery © <a href="http://mapbox.com">Mapbox</a>',
        id: 'examples.map-i875mjb7'
    }).addTo(map);
        getMarkers();
        map.on('moveend', onMapMove); 

};

function getMarkers(){ var center = map.getCenter(); var zoo = map.getZoom(); var bounds = map.getBounds(); var min = bounds.getSouthWest().wrap(); var max = bounds.getNorthEast().wrap(); var Membersx = ""; var poly = ""; var values = []; var coord = []; var heatMap = ""; var HeatMapActiveLayer = $("#active_heatmap").val(); var heatMap = new L.TileLayer.HeatCanvas({},{ 'step': 0.1, 'degree': HeatCanvas.LINEAR, 'opacity': 0.5 });

$.ajax({
    type: "post", 
    url: "/geojsonData", 
    dataType: "json", 
    data: {clat:center.lat, clng:center.lng, zoom:zoo, minlat:min.lat, minlng:min.lng, maxlat:max.lat, maxlng:max.lng, layers:<?php echo json_encode($layers); ?>}, 
    success: function(result){

      //Removing existing Polygon Layers...
        $.each(result, function(index, layer) {
            for(i in map._layers) {
               if(typeof map._layers[i].feature != undefined){
                    if(typeof map._layers[i].feature.code == $("#active_heatmap").val()){
                        map.removeLayer(map._layers[i]);
                    }
                }   
            }
        });

        $.each(result, function(index, layer) {
            if(typeof(layer) != "undefined") {
                if(layer.data.entity == 'PYG'){ // Layer type is polygon
                    $.each(layer.data.features, function(index, polygons) {
                        var coordinates = JSON.parse(polygons.geometry.coordinates);
                        var values = [];
                        var coord = [];
                        for(var i = 0, l = coordinates.length; i < l; i++) {
                            values.push(coordinates[i]);
                        }   
                        coord.push(values);
                        var campus = {
                                'type': 'Feature',
                                'code': polygons.code,
                                'properties': {
                                        'name': polygons.properties.name, 
                                        'category': polygons.properties.category,
                                        'description': polygons.properties.description,
                                        'style': {
                                            weight: 2,
                                            color: polygons.properties.style.color,
                                            opacity: 1,
                                            fillColor: polygons.properties.style.color,
                                            fillOpacity: 0.4
                                        }},
                                'geometry': {
                                        'type': 'Polygon', 
                                        'coordinates': coord
                                    }
                        };

                        var poly =  L.geoJson(polygonData,  {
                                                    style: function (feature) {
                                                        return feature.properties && feature.properties.style;
                                                    },
                                                    onEachFeature: onEachPolygonFeature,
                        });
                        map.addLayer(poly); 
                    });
                }else{
                    if (layer.data.layer == $("#active_heatmap").val()) { // Layer type is activited for HeatMap
                        $.each(layer.data.features, function(features, latlng) {
                            heatMap.pushData(latlng.geometry.coordinates[1], latlng.geometry.coordinates[0], 3);
                            if(heatMap) { 
                                var mainLayers = {
                                    "heatMap": heatMap
                                };
                            } 
                        });
                        map.addLayer(heatMap);
                    }else{ 
                        Membersx = new L.geoJson(layer.data ,{
                            pointToLayer: function(feature, latlng) {
                                if(feature.geometry.type == 'Point'){ 
                                    return L.marker(latlng, {icon: L.ExtraMarkers.icon({
                                                                        icon: feature.marker_icon,
                                                                        markerColor: feature.marker_color,
                                                                        shape: feature.marker_type,
                                                                        prefix: 'fa'
                                                                    }) })
                                }
                            }, 
                            onEachFeature: onEachFeature
                        });
                        map.addLayer(Membersx);
                    }
                }
            }
        });
    }                       
});

}

Whenever i use the basic function to remove the active layer for the heatmap. I get this following error..

Uncaught TypeError: Cannot read property 'code' of undefined

if(typeof map._layers[i].feature != undefined){ if(typeof map._layers[i].feature.code == $("#active_heatmap").val()){ map.removeLayer(map._layers[i]); } }

Help me please to resolve this bug.

Copied from original issue: tombatossals/angular-leaflet-directive#636

[luxigo]

+1 for a way to get a list of active layers without looking at the DOM... It seems that baselayerchange and overlayadd events are not fired (or not received) at directive initialization time.