Trim and export visible layer(s) as two PNG images (standard and retina)

iOS → Save for Retina.jsx

var fileName = prompt('Image name', 'image');
if (null != fileName)
{
    var selection = activeDocument.selection;
    
    try
    {
        selection.copy(true);
    }
    catch (error)
    {
         selection.selectAll();
         selection.copy(true);
    }

    var width = selection.bounds[2].value - selection.bounds[0].value;
    var height = selection.bounds[3].value - selection.bounds[1].value;
    documents.add(width, height, 72, "Untitled", NewDocumentMode.RGB, DocumentFill.TRANSPARENT);

    activeDocument.paste(false);
    activeDocument.trim(TrimType.TRANSPARENT);

    var options = new  ExportOptionsSaveForWeb();
    options.format = SaveDocumentType.PNG;
    options.PNG8 = false;

    var file;

    file = new File('~/Desktop/' + fileName + '@2x.png');
    activeDocument.exportDocument (file, ExportType.SAVEFORWEB, options);

    activeDocument.resizeImage('50%', '50%', 72, ResampleMethod.BICUBICSHARPER);
    file = new File('~/Desktop/' + fileName + '.png');
    activeDocument.exportDocument (file, ExportType.SAVEFORWEB, options);

    activeDocument.close(SaveOptions.DONOTSAVECHANGES);
}