generatePdfAutoDownload.js

const pdfMakePrinter = require('pdfmake/src/printer');

function generatePdf(docDefinition, callback) => {
  try {
    const fontDescriptors = { ... };
    const printer = new pdfMakePrinter(fontDescriptors);
    const doc = printer.createPdfKitDocument(docDefinition);
    
    let chunks = [];
    const result;

    doc.on('data', (chunk) => {
      chunks.push(chunk);
    });

    doc.on('end', () => {
      result = Buffer.concat(chunks);
      callback(result);
    });
    
    doc.end();
    
  } catch(err) {
    throw(err);
  }
};

app.get("/pdf", function(req, res) {
  const docDefinition = { content: "Dummy content" };

  generatePdf(
    docDefinition,
    function(binary) {
      res.contentType("application/pdf");
      res.send(binary);
    },
    function(error) {
      res.send("ERROR:" + error);
    }
  );
});