Indexes items tree in cycle

Hi,
I add items in the tree programatically. When I click on an item in the tree, I can get the index of the item.
How can I get index of the item programatically used this code?
for(var x=1; x<=tree[0].length; x++)
{
for(var y=1; y<=tree[x].length; y++)
{
alert(....);
}
}

Or how can I get indexes of the items tree in cycle programatically?

Thanks.