Return true if the marker is visible.
<div id="map_canvas">
<span class="smallPanel"><button>marker.isVisible() = true</button></span>
</div>
var div = document.getElementById("map_canvas");
var map = plugin.google.maps.Map.getMap(div);
// Add a marker
var marker = map.addMarker({
'position': {
lat: 0,
lng: 0
}
});
var button = div.getElementsByTagName('button')[0];
button.addEventListener("click", function() {
if (marker.isVisible()) {
marker.setVisible(false);
} else{
marker.setVisible(true);
}
button.innerHTML = "marker.isVisible() = " + marker.isVisible();
});