Mine

var l = map.layers[1];for(var i = 0; i < l.features.length; i++){    var f = l.features[i];    f.style = {display : 'none' };    l.drawFeature(f);}alert('features hidden');for(var i = 0; i < l.features.length; i++){    var f = l.features[i];    delete f.style    l.drawFeature(f);}