ps-export-layers-to-png.jsx

#target photoshop
// $.level = 2;

/*
 *  Script by Tomek Cejner (tomek (at) japko dot info)
 *  based on work of Damien van Holten:
 *  http://www.damienvanholten.com/blog/export-groups-to-files-photoshop/
 *
 *  My version adds support of nested layer groups, 
 *  and exports single layers in addition to groups. 
 *
 */

function main(){
if(!documents.length) return;
var doc = activeDocument;
var oldPath = activeDocument.path;

var outFolder = new Folder(oldPath + "/out");
if (!outFolder.exists) {
    outFolder.create();
}

scanLayerSets(doc);

function scanLayerSets(el) {
    // find layer groups
    for(var a=0;a<el.layerSets.length;a++){
        var lname = el.layerSets[a].name;
        if (lname.substr(-4) == ".png") {
            saveLayer(el.layers.getByName(lname), lname, oldPath, true);
        } else {
            // recursive
            scanLayerSets(el.layerSets[a]);
        }
    }
    

    // find plain layers in current group whose names end with .png
    for(var j=0; j<el.artLayers.length; j++) {
        var name = el.artLayers[j].name;
        if (name.substr(-4) == ".png") {
            saveLayer(el.layers.getByName(name), name, oldPath, false);
        }
    }

}

function saveLayer(layer, lname, path, shouldMerge) {
    activeDocument.activeLayer = layer;
    dupLayers();
    if (shouldMerge === undefined || shouldMerge === true) {
        activeDocument.mergeVisibleLayers();
    }
    activeDocument.trim(TrimType.TRANSPARENT,true,true,true,true);
    var saveFile= File(path +"/out/"+lname);
    SavePNG(saveFile);
    app.activeDocument.close(SaveOptions.DONOTSAVECHANGES);
}

};

main();

function dupLayers() { 
    var desc143 = new ActionDescriptor();
        var ref73 = new ActionReference();
        ref73.putClass( charIDToTypeID('Dcmn') );
    desc143.putReference( charIDToTypeID('null'), ref73 );
    desc143.putString( charIDToTypeID('Nm  '), activeDocument.activeLayer.name );
        var ref74 = new ActionReference();
        ref74.putEnumerated( charIDToTypeID('Lyr '), charIDToTypeID('Ordn'), charIDToTypeID('Trgt') );
    desc143.putReference( charIDToTypeID('Usng'), ref74 );
    executeAction( charIDToTypeID('Mk  '), desc143, DialogModes.NO );
};

function SavePNG(saveFile){
    var pngOpts = new ExportOptionsSaveForWeb; 
    pngOpts.format = SaveDocumentType.PNG
    pngOpts.PNG8 = false; 
    pngOpts.transparency = true; 
    pngOpts.interlaced = false; 
    pngOpts.quality = 100;
    activeDocument.exportDocument(new File(saveFile),ExportType.SAVEFORWEB,pngOpts); 
}