// Apply new JSON when the user selects a different style.
styleSelector.addEventListener('change', function() {
map.setOptions({styles: styles[styleSelector.value]});
});
<div id="style-selector-control" class="map-control">
<select id="style-selector" class="selector-control">
<option value="default">Default</option>
<option value="silver">Silver</option>
<option value="night">Night mode</option>
<option value="retro" selected="selected">Retro</option>
<option value="hiding">Hide features</option>
</select>
</div>