How to listen for user generated zoom in Google Maps?

Question

I want to know when a Google Maps zoom_changed event is fired specifically by a user interaction with the +/- zoom buttons. If I use a general event listener for zoom_changed,

Answer 1

I was looking to do the same thing. I was hoping to find that there was a way built into the Google Maps API, but at a minimum, you should be able to store the starting zoom level as a variable when you initialize the map. Then, compare the result of getZoom() to it to know whether it was a zoom in or a zoom out.

For example:

map = new google.maps.Map(document.getElementById('map_canvas'), { zoom: 11 });
var previous_zoom = 11;

google.maps.event.addListener(map,'zoom_changed',function(){
  if(map.getZoom() > previous_zoom) {
    alert('You just zoomed in.');
  }
  previous_zoom = map.getZoom();
}