How do I fade out a circle in a Google Map, x seconds after I've added it to the map?

Question

What I basically had in mind is what Google did in this example

Every second I want to add circles at certain coordinates and then slowly fade them out. I already ma

Answer 1

To fade them out you need to decrease the opacity of the fill and the stroke until it is 0.0.

setInterval(fadeCityCircles,1000);

function fadeCityCircles() {
  for (var city in citymap) {
    var fillOpacity = citymap[city].cityCircle.get("fillOpacity");
    fillOpacity -= 0.02;
    if (fillOpacity < 0) fillOpacity =0.0;
    var strokeOpacity = citymap[city].cityCircle.get("strokeOpacity");
    strokeOpacity -= 0.05;
    if (strokeOpacity < 0) strokeOpacity =0.0;
    citymap[city].cityCircle.setOptions({fillOpacity:fillOpacity, strokeOpacity:strokeOpacity});
  }
}  

example