[OpenLayers-Users] Do not re-add markers...

[Max Allan Niklasson]

 I've made a script, that is make an ajax-request when I zoomed into 
 level 10, then it add markers. Afterwords when I zoom into 11 and then 
 out to 10, the markers is being re-added to the map... Is there a way to 
 not have it like this?

 My code....
 **************************************************
 map.events.register("zoomend", null, function(){
 	if(map.zoom == 10){
 	var bounds = map.getExtent();
 	console.log(bounds);
 	var ne = new 
 OpenLayers.LonLat(bounds.right,bounds.top).transform(map.getProjectionObject(),wgs84);
 	var sw = new 
 OpenLayers.LonLat(bounds.left,bounds.bottom).transform(map.getProjectionObject(),wgs84);
 	var vectorLayer = new OpenLayers.Layer.Vector();
 	map.addLayer(vectorLayer);
 	$.getJSON('ajax.php?a=markers&type=json&sw=('+sw.lon+','+sw.lat+')&ne=('+ne.lon+','+ne.lat+')',function(data){//GeoJSON
 	//$.getJSON('test.json',function(data){
 	   var geojson_format = new OpenLayers.Format.GeoJSON({
 		'externalProjection': wgs84,
 		'internalProjection': baseProjection
 	    });
             vectorLayer.addFeatures(geojson_format.read(data));
 	});
     }
 });
 **************************************************
 Best regards
 The Red Kite