To replace text or images in a PDF.

const doc = await PDFNet.PDFDoc.createFromURL(filename);
const replacer = await PDFNet.ContentReplacer.create();
const page = await doc.getPage(1);

// replace an image on the page
const target_region = await page.getMediaBox();
const img = await PDFNet.Image.createFromURL(doc, imagename);
await replacer.addImage(target_region, await img.getSDFObj());

// replace a text placeholder
await replacer.addString('NAME', 'John Smith');

// replace text in a given region
String text = "hello world";
await replacer.addText(target_region, text);
await replacer.process(page);

Replace PDF text or images
Full code sample which shows how to use pdftron.PDF.ContentReplacer to search and replace text strings and images in existing PDF (e.g. business cards and other PDF templates).