Semi-Transparent Layer

Example of a map with a semi-transparent layer.

This example will display a tiled MaxBox layer semi-transparently over an OSM background.

<!DOCTYPE html>
<html>
  <head>
    <title>Semi-Transparent Layer</title>
    <link rel="stylesheet" href="https://openlayers.org/en/v4.6.4/css/ol.css" type="text/css">
    <!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
    <script src=""></script>
    <script src="https://openlayers.org/en/v4.6.4/build/ol.js"></script>
  </head>
  <body>
    <div id="map" class="map"></div>
    <script>
      var map = new ol.Map({
        layers: [
          new ol.layer.Tile({
            source: new ol.source.OSM()
          }),
          new ol.layer.Tile({
            source: new ol.source.TileJSON({
              url: 'https://api.tiles.mapbox.com/v3/mapbox.va-quake-aug.json?secure',
              crossOrigin: 'anonymous'
            })
          })
        ],
        target: 'map',
        view: new ol.View({
          center: ol.proj.fromLonLat([-77.93255, 37.9555]),
          zoom: 7
        })
      });
    </script>
  </body>
</html>