Add a new PDF Layer in Node.js

async function main() {
  let doc = await PDFNet.PDFDoc.create();
  const builder = await PDFNet.ElementBuilder.create();
  const writer = await PDFNet.ElementWriter.create();

  // Create a layer
  const imageLayer = await PDFNet.OCG.create(doc, 'Image Layer');
  const cfg = await PDFNet.OCGConfig.create(doc, true);
  cfg.setName('Default');

  // Add the new OCG to the list of layers that should appear in PDF viewer GUI.
  let layerOrderArray = await doc.createIndirectArray();
  cfg.setOrder(layerOrderArray);
  layerOrderArray.pushBack(await image_layer.getSDFObj());

  // Start a new page
  const page = await doc.pageCreate();
  writer.beginOnPage(page); // Begin writing to the page

  // Add new content to the page and associate it with one of the layers.
  const nullEncoderHints = new PDFNet.Obj('0');
  const img = await PDFNet.Image.createFromURL(doc, imagename, nullEncoderHints);
  const img_obj = await img.getSDFObj();
  img_obj.put('OC', imageLayer);
  writer.writePlacedElement(await builder.createImageScaled(img, 300, 600, 200, -150));
  await writer.end();   // save changes to the current page
  doc.pagePushBack(page);
}
PDFNet.runWithCleanup(main);