Detect if marker is within circle overlay on Google Maps (Javascript API V3)

Question

I have markers dotted around a map, and a radius (circle overlay) on a marker marking your location (which changes every time you move). Is there any way I can check to see

Answer 1

google.maps.Circle.prototype.contains = function(latLng) {
  return this.getBounds().contains(latLng) && google.maps.geometry.spherical.computeDistanceBetween(this.getCenter(), latLng) <= this.getRadius();
}