Google Maps setIcon to update path (not URL) - google-maps-api-3

Question

I can't seem to find any documentation about updating the path of an icon (marker) in the Google Maps API. In this particular example I'm trying to change the fillOpacity of the icon from 0 to 1.
var myIcon = {
path: google.maps.SymbolPath.CIRCLE,
scale: 5,
fillColor: "#ff00ff",
fillOpacity: 0,
strokeColor: "#ff00ff",
strokeWeight: 2
};
var marker = new google.maps.Marker({
position: position,
icon: myIcon,
map: map,
title: 'My Marker>'
});
marker.addListener('click', function() {
this.setOptions({icon:{fillOpacity: 0.5}}); // Not working
this.setIcon({fillOpacity: 0.2}); // Not working either
});

Answer 1

The "icon" is an anonymous object. You need to set the whole object again:
marker.addListener('click', function() {
myIcon.fillOpacity = 0.5;
this.setIcon(myIcon);
});
or:
marker.addListener('click', function() {
myIcon.fillOpacity = 0.5;
this.setOptions({
icon: myIcon
});
});
proof of concept fiddle
code snippet:
function initMap() {
var map = new google.maps.Map(document.getElementById('map'), {
zoom: 4,
center: {
lat: -25.363882,
lng: 131.044922
}
});
var myIcon = {
path: google.maps.SymbolPath.CIRCLE,
scale: 5,
fillColor: "#ff00ff",
fillOpacity: 0,
strokeColor: "#ff00ff",
strokeWeight: 2
};
var marker = new google.maps.Marker({
position: map.getCenter(),
icon: myIcon,
map: map,
title: 'My Marker>'
});
marker.addListener('click', function() {
myIcon.fillOpacity = 0.5;
this.setIcon(myIcon);
});
}
html,
body,
#map {
height: 100%;
margin: 0;
padding: 0;
}
<div id="map"></div>
<!-- Replace the value of the key parameter with your own API key. -->
<script async defer src="https://maps.googleapis.com/maps/api/js?key=AIzaSyCkUOdZ5y7hMm0yrcCQoCvLwzdM6M8s5qk&callback=initMap"></script>