> hi ross, i dont understand how to define relation between batch[] and
> marker[] you can see code by
> viewsourcehttp://www.spotonsearch.co.uk/auto/xx/index.html
Well, we can ignore that now because your code no longer includes
reference to marker[]
I think you need to review your logic here
You have a global array batch[], which contains only the 'id' of all
loaded markers.
When you load new markers, you check to see if each new marker's id is
already known in batch[], and if it isn't, you add the marker to your
map and save its 'id' in batch[]. If the marker's id is actually
already in batch[], you do nothing - it's already added to the map.
So far, so good.
You've got some code in the add-new-marker section that tries to
remove some overlay, though its not clear what. I can't see any
reason to try to remove an overlay just because you've added a new
marker.
The missing part seems to be looking at the batch[] array after adding
a set of new markers, and removing any markers that weren't present in
this update. Even if that were done, you'd have trouble removing
existing markers from the map because you have kept no reference to
them; each was created only in local scope in the previous run of
updateMarkers().
There's more than one way to go about this, but this could be one
approach:
You need to remember the id's of markers that you've put on the map,
and you also need to keep a reference to each of those markers in case
you need to remove it some time later.
You could combine those requirements by indexing your batch[] storage
array by the marker 'id' (I assume they are unique!) and storing the
whole marker
In your updateMarkers(), instead of
batch.push(id);
var marker = createMarker(....
do
var marker = createMarker(....
batch[id] = marker;
You'd need to change the 'does it already exist' test from
for(ii=0; ii<batch.length; ii++)
{ if(batch[ii]=== id)
...
to something as simple as
if ( batch[id] ) { ...
there's no need to loop, as you can address batch[] directly by 'id'
and you just want to know if that entry exists or not.
If it doesn't exist, you go on to make a new marker.
If it does already exist, you need some means to distinguish between
batch[] entries that have been found (because you want to keep them),
and those that haven't (because you want to remove them later).
One way to do that might be to set a flag on each batch[] item. So,
when a 'new' marker is found already in batch[id], do something like -
batch[id].keep_it = true;
There's a trap here if you're not careful - you need to go back to the
create-a-new-marker section and set the .keep_it flag there as well.
After you've finished processing all the incoming markers data, and
either creating new markers or keeping existing ones, you need to scan
batch[] for the redundant ones.
Run a loop through each batch[] entry by id - for (id in batch) - and
test the .keep-it flag.
If the flag is set, clear it down ready for the next updateMarkers()
session - batch[id].keep_it = false;
else
remove the marker from the map - map.removeOverlay(batch[id]);
and of course clear it from the array - delete batch[id];
There would be cleverer ways to go about it, by not really destroying
'old' markers but just hiding them in case we might use them again
later. And you could make it more efficient by doing things like
testing for the id before bothering to read the rest of the XML data.
But get the basics working first.
cheers, Ross K
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