maptalks - 添加图层和移除图层

添加图层和移除图层
index.html
<!DOCTYPE html>
<html>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>图层 - 添加图层和移除图层</title>
  <style type="text/css">
    html,body{margin:0px;height:100%;width:100%}
    .container{width:100%;height:100%}
    .pane{background:#34495e;line-height:28px;color:#fff;z-index:10;position:absolute;top:20px;right:20px}
    .pane a{display:block;color:#fff;text-align:left;padding:0 10px;min-width:28px;min-height:28px;float:left}
  </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>
    <div class="pane"><a href="javascript:add();">Add layer</a><a href="javascript:remove();">Remove Layer</a></div>

    <script>

      var map = new maptalks.Map('map', {
        center: [-0.113049,51.498568],
        zoom: 14,
        baseLayer: new maptalks.TileLayer('base', {
          urlTemplate: 'https://{s}.basemaps.cartocdn.com/light_all/{z}/{x}/{y}.png',
          subdomains: ['a','b','c','d'],
          attribution: '&copy; <a href="http://osm.org">OpenStreetMap</a> contributors, &copy; <a href="https://carto.com/">CARTO</a>'
        })
      });

      var marker = new maptalks.Marker(
        map.getCenter(),
        {
          symbol : {
            'textName' : 'Layer is added.',
            'textWeight' : 'bold',
            'textSize' : 50,
            'textFill' : '#1bbc9b',
            'textHaloFill' : '#fff',
            'textHaloRadius' : 5
          }
        }
      );
      var layer = new maptalks.VectorLayer('vector', [marker])
        .addTo(map);

      function add() {
        map.addLayer(layer);
      }

      function remove() {
        map.removeLayer(layer);
      }

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