title: Mapbox gl js Add a Marker from firebase database
body: <p>I want to add some costumized markers to my mapbox map based on my firebase database but i don't know how.</p>
  
  <p>So i got my gotData function that receives the latitude and longitude from my database</p>
  
  <pre><code>    function gotData(data) {
  
    console.log(data.val());
    var dados = data.val();
    var keys = Object.keys(dados);
   // console.log(keys);
  for (var i = 0; i &lt; keys.length; i++) {
      var k = keys[i];
      var latitude = dados[k].latitude;
      var longitude = dados[k].longitude;
      //console.log(latitude, longitude);
      var li = createElement('li', latitude + ': ' + longitude);   
  }   
  
  }
  </code></pre>
  
  <p>And I have placed on my HTML file a code to add a Marker but I don't know what to put inside the "coordinates":</p>
  
  <pre><code>mapa.on('load', function () {
  mapa.addLayer({
      "id": "points",
      "type": "symbol",
      "source": {
          "type": "geojson",
          "data": {
              "type": "FeatureCollection",
              "features": [{
                  "type": "Feature",
                  "geometry": {
                      "type": "Point",
                      "coordinates": [What goes here?]
                  },
                  "properties": {
                      "title": "title",
                      "icon": "circle"
                  }
              }]
          }
      },
      "layout": {
          "icon-image": "{icon}-15",
          "text-field": "{title}",
          "text-font": ["Open Sans Semibold", "Arial Unicode MS Bold"],
          "text-offset": [0, 0.6],
          "text-anchor": "top"
      }
  });
  </code></pre>
  
  <p>});</p>
  
  <p>Any tips are welcome</p>