问如何添加图标来动态切换mapboxgl样式？

EN

mapboxgl.accessToken = 'pk.eyJ1IjoiZmFyYWRheTIiLCJhIjoiTUVHbDl5OCJ9.buFaqIdaIM3iXr1BOYKpsQ';
let map = new mapboxgl.Map({
  container: 'map',
  style: 'mapbox://styles/mapbox/streets-v9', 
  center: [-1.77, 52.73],
  zoom: 3,
});

let icon = document.getElementById('icon');

icon.addEventListener('click', function(e) {
	map.setStyle('mapbox://styles/mapbox/light-v9');
}, false)

#icon {
  position: absolute;
  top: 15px;
  left: 15px;
  color: black;
}

#map {
  height: 500px;
}

<link href="https://api.tiles.mapbox.com/mapbox-gl-js/v0.38.0/mapbox-gl.css" rel="stylesheet"/>
<script src="https://api.tiles.mapbox.com/mapbox-gl-js/v0.38.0/mapbox-gl.js"></script>

<div id="map"></div>

<button id="icon">
Switch layers
</button>

function LayerSwitchControl() { }

LayerSwitchControl.prototype.onAdd = function(map) {
    this._map = map;
    this._container = document.createElement('div');
    this._container.className = 'mapboxgl-ctrl';
    // change this next line to include a layer-switching icon
    this._container.textContent = 'Hello, world';
    return this._container;
};

LayerSwitchControl.prototype.onRemove = function () {
     this._container.parentNode.removeChild(this._container);
     this._map = undefined;
};