{ // Get the active comp comp = app.project.activeItem; // Make sure the active item is a Comp if (!comp || !(comp instanceof CompItem)) { alert("Please select a composition first!"); } else { // Get all selected layers layers = comp.selectedLayers; // Iterate through all selected layers for (var i = 0; i < layers.length; i++) { // Create a null layer var nullLayer = comp.layers.addNull(); nullLayer.name = layers[i].name + "_null"; // Position the null layer above the current layer nullLayer.moveBefore(layers[i]); } } }