Automatically adjust zoom to accommodate all marker in a google map

Google Maps API v3 provides a LatLngBounds object to which you can add multiple LatLng objects. You can then pass this to Map.fitBounds() function as described here:

• Zoom-To-Fit All Markers, Polylines or Polygons on A Google Map – API v2
• Zoom-to-Fit All Markers on Google Map v3

Partial Example

var latlng = [
    new google.maps.LatLng(1.23, 4.56),
    new google.maps.LatLng(7.89, 1.01),
    // ...
]; 
var latlngbounds = new google.maps.LatLngBounds();
for (var i = 0; i < latlng.length; i++) {
    latlngbounds.extend(latlng[i]);
}
map.fitBounds(latlngbounds);