maptalks - 添加多个瓦片图层

添加多个瓦片图层
index.html
<!DOCTYPE html>
<html>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>瓦片图层与地理投影 - 添加多个瓦片图层</title>
  <style type="text/css">
    html,body{margin:0px;height:100%;width:100%}
    .container{width:100%;height:100%}
  </style>
  <link rel="stylesheet" href="https://unpkg.com/maptalks/dist/maptalks.css">
  <script type="text/javascript" src="https://unpkg.com/maptalks/dist/maptalks.min.js"></script>
  <body>
    <div id="map" class="container"></div>

    <script>
      var map = new maptalks.Map('map', {
        center:     [-0.113049,51.498568],
        zoom:  6,
        pitch : 40,
        baseLayer : new maptalks.TileLayer('base',{
          'urlTemplate': 'https://{s}.basemaps.cartocdn.com/dark_nolabels/{z}/{x}/{y}.png',
          'subdomains'  : ['a','b','c','d']
        }),
        // additional TileLayers in create options
        layers : [
          new maptalks.TileLayer('boudaries',{
            'urlTemplate': 'https://{s}.basemaps.cartocdn.com/dark_only_labels/{z}/{x}/{y}.png',
            'subdomains'  : ['a','b','c','d']
          })
        ]
      });

    </script>
  </body>
</html>