Leaflet displaying a single GeoJSON layer even though multiple are supplied

Question

I have a simple Leaflet map and I am trying to display multiple point layers. I know this question has been asked quite a few times and I have tried every single solution but didn't work.

I get valid GeoJSONs (valid because I can display them individually) from two URLs. I can load the layers in my map and the map.hasLayer() returns true for both layers. But the map only displays the last layer, the first layer is not displayed.

I have tried different HTTP calls using Axios, jQuery, and plain XMLHTTPRequest too but the same behavior.

Logging the JSONs to the console shows that one layer has 0 features even though I am using the same code to load the second layer.

layer 1 console log

Object { type: "FeatureCollection", features: [] }
​
features: Array []
​
type: "FeatureCollection"
​
<prototype>: Object { … }

layer 2 console log

Object { type: "FeatureCollection", features: (5427) […] }
​
features: Array(5427) [ {…}, {…}, {…}, … ]
​
type: "FeatureCollection"
​
<prototype>: Object { … }

Is Leaflet overwriting on the features of the first layer?

Here is my code:

BASECOORDS = [51.96236, 7.62571];


var TILE_URL = "https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png";
var MB_ATTR = 'Map data &copy; <a href="http://openstreetmap.org">OpenStreetMap</a> contributors';
mymap = L.map('llmap').setView(BASECOORDS, 13);
L.tileLayer(TILE_URL, {attribution: MB_ATTR}).addTo(mymap);

var ParkingLayer = null;
var TransLayer = null;

findNearby = function () {
    $.getJSON('/parking',
        function (geojsonPark) {
            ParkingLayer = L.geoJson(geojsonPark),
            console.log(geojsonPark)
            ParkingLayer.addTo(mymap);  
            return ParkingLayer
            });
};

findNearby2 = function () {
    $.getJSON('/trans',
        function (geojsonTrans) {
            TransLayer = L.geoJson(geojsonTrans),
            console.log(geojsonTrans)
            TransLayer.addTo(mymap);
            return TransLayer;
            });
};
findNearby()
findNearby2()

Answer 1

I have 6 big GeoJSONs with 3000-4000 features each. I am running local version of PostgreSQL though. The GeoJSONs are not files, but PostGIS geometries and I convert them to GeoJSONs.

With setTimeout, I am now executing GeoJSON requests at different intervals and waiting for on request to be completed before executing the next query.

Now all the layers display correctly.