Leaflet test geoJSON

HTML

<link rel="stylesheet" href="https://unpkg.com/[email protected]/dist/leaflet.css">
<script src="https://unpkg.com/[email protected]/dist/leaflet.js"></script>
<script src="https://yigityuce.github.io/Leaflet.Control.Custom/Leaflet.Control.Custom.js"></script>
<script src="https://unpkg.com/@turf/[email protected]/turf.min.js"></script>
<link rel="stylesheet" href="https://ghinda.net/css-toggle-switch/dist/toggle-switch.css">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<div id="map" class="map"></div>

CSS

html, body {
    height: 100%;
    width: 100%;
    padding: 0;
    margin: 0;
    border: 0;
    }
.map {
	height: 100%;
	width: 100%;
    }

.switch-toggle > label {
            outline-style: none!important;
    }

JavaScript

var mailles = {
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "geometry": {
        "type": "MultiPolygon",
        "coordinates": [
          [
            [
              [
                0.229628794333224,
                48.4029232602356
              ],
              [
                0.227257067602151,
                48.447877739469
              ],
              [
                0.294831380624158,
                48.449437687249
              ],
              [
                0.297145397674823,
                48.4044819277577
              ],
              [
                0.229628794333224,
                48.4029232602356
              ]
            ]
          ]
        ]
      },
      "properties": {
        "id_maille": 1,
        "dateobs": "2010-06-26",
        "annee": 2010,
        "nb_observations": 1
      }
    },
    {
      "type": "Feature",
      "geometry": {
        "type": "MultiPolygon",
        "coordinates": [
          [
            [
              [
                0.222501415605553,
                48.5377818505448
              ],
              [
                0.220117469417105,
                48.5827314251312
              ],
              [
                0.287865504207965,
                48.5842952209079
              ],
              [
                0.290191444099058,
                48.5393443624496
              ],
              [
                0.222501415605553,
                48.5377818505448
              ]
            ]
          ]
        ]
      },
      "properties": {
        "id_maille": 2,
        "dateobs": "2010-06-26",
        "annee": 2008,
        "nb_observations": 10
      }
    },
    {
      "type": "Feature",
      "geometry": {
        "type": "MultiPolygon",
        "coordinates": [
          [
            [
              [
                -0.17810004488886,
                48.4377102799765
              ],
              [
               ...