exportSelectedLayer.jsx

/*
<javascriptresource>
<name>Export Selected Layer</name>
<about></about>
<category>PsScripts</category>
<enableinfo>true</enableinfo>
</javascriptresource>
*/

main();

function layerDuplicate(layer) {
	switch (layer.typename) {
		case 'ArtLayer':
			return artLayerDuplicate(layer);
			break;
		case 'LayerSet':
			return layerSetDuplicate(layer);
			break;
		default:
			alert(layer.typename);
	}
}

function main() {
	var doc = activeDocument;
	var layer = doc.activeLayer;
	
	var targetLayer = layerDuplicate(layer);
	
	var bounds = targetLayer.bounds;
	
	targetLayer.translate(-bounds[0], -bounds[1]);
	targetLayer.copy();
	
	var newDocRef = app.documents.add(bounds[2], bounds[3], doc.resolution, name, NewDocumentMode.RGB, DocumentFill.TRANSPARENT);
	newDocRef.paste();
	
	newDocRef.trim(TrimType.TRANSPARENT, true, true, true, true);
		
	activeDocument = doc;
	targetLayer.remove();
	
	activeDocument = newDocRef;
}

function layerSetDuplicate(layer) {
	var duppedLayer = layer.duplicate();
	return duppedLayer.merge();
}

function artLayerDuplicate(layer) {
	var layerset = activeDocument.layerSets.add();
	var duppedLayer = layer.duplicate(layerset);
	
	return layerset.merge();
}