toggle layer visibility

This thread has helped me. I only needed to toggle a named layer. This is the Javascript that works for me. Perhaps someone else will find it useful.

app.activeDocument.layers.getByName('LayerNameHere').visible ^= 1;

If I understand what you are asking the script below will toggle the layer visibility of the layer below the active/selected layer. It works with layerSets. If the selected layer is at the bottom of the stack/set, the script does nothing.

var curentLayer = app.activeDocument.activeLayer;
var curentParent = curentLayer.parent;
var currentIndex = getLayerIndex( curentParent, curentLayer );
if(currentIndex != (curentParent.artLayers.length-1)){
    curentParent.artLayers[currentIndex+1].visible= !curentParent.artLayers[currentIndex+1].visible;
}
function getLayerIndex( parent, layer ){
    for(var i=0;i<parent.artLayers.length;i++){
        if(parent.artLayers==layer) return i;
    }
};