Check if WMS layer is queryable in OpenLayers?

Question

I'm running a map with lots of different WMS layers published by GeoServer. Some of them are queryable, some of them are not. How can I tell that with OpenLayers API?

I'm requesting GetFeatureInfo and I need to request only the queryable layers, layers with queryable param set to false always return "Layer is not queryable" when requested - and that's what I want to hide from users. I looked into OpenLayers.Map.layers and found no "queryable" property.

UPDATE (to the first comment): This works fine as long as I use it with localhost:8080/geoserver/wms?service=WMS&version=1.1.1&request=GetCapabilities&. When I tried to get capabilities from http://www.edpp.cz:8080/geoserver/wms?service=WMS&version=1.1.1&request=GetCapabilities&, I got empty array of layers as a result.

I'm trying it with the following code:

function getCapabilities(offline) {
    var url = '';
    if (offline) {
        url = 'localhost:8080/geoserver/wms?service=WMS&version=1.1.1&request=GetCapabilities&';
    }
    else {
        url = 'http://www.edpp.cz:8080/geoserver/wms?service=WMS&version=1.1.1&request=GetCapabilities&'
    }
    var layers = []
        ,result
        ,request = OpenLayers.Request.GET({
            url: url
            ,success: function(response) {
                var format = new OpenLayers.Format.XML()
                    ,xml = format.read(response.responseText)
                    ,text = format.write(xml)
                    ,CAPformat = new OpenLayers.Format.WMSCapabilities()
                    ,cap = CAPformat.read(xml);
                    if (cap.capability) {
                        for (var len = cap.capability.layers.length-1; len >= 0; len -= 1) {
                            if (cap.capability.layers[len].queryable) {
                                layers.push(cap.capability.layers[len].name);
                            }
                        }
                    }
            }
        });
    return layers; //ARRAY
}

Answer 1

The queriable information is contained in the WMS capabilities document, the one that gets returned when you hit http://host:port/geoserver/ows?request=GetCapabilities&service=WMS

OpenLayers has this class to parse it: http://dev.openlayers.org/docs/files/OpenLayers/Format/WMSCapabilities-js.html