Strange problem with object property - present outside of loop, missing inside of loop

I have a really strange problem right now.

markers is an array of objects.

0  
     content (String)
     coords (Object)
     gMarker (Object)
1  
     content (String)开发者_JAVA百科
     coords (Object)
     gMarker (Object)
2  
     content (String)
     coords (Object)
     gMarker (Object)

So far, so good.

The problem:

console.dir(markers); 
/**
 * output as expected
 */
for(var i in markers) {
    console.dir(markers[i]); 
    /** 
     * gMarker object is missing!
     * markers[i] suddenly consists just of content and coords
     */

How can that be?

Edit: It must have had something to do with the "load" callback function of google maps. It fires a bit too early, at least in my case. I replaced that callback (GEvent.addListener(map, "load", callback_fn)) with a simple setTimeout that fires my callback function after 2 seconds, and now everything works as expected.

Either way, this does not explain why the gMarker property is not available inside that for-loop, that can not even be a race condition since the loop starts immediately after that point where the object is still OK.

Shouldn't that be

for(var i in markers) {
    console.dir(i); 

It's weird, my Firebug console.dir doesn't even work with for-in on an array.

It could have to do with i being a global variable set elsewhere, but more than likely this is called due to the property being loaded at a later point in time. Do you manually set the object, or how is it being loaded?

for (var i=markers.length;i--;){
   console.dir(markers[i]);
}