Get PDFKit as base64 string

Synchronous option not (yet) present in the documentation

const doc = new PDFDocument();
doc.text("Sample text", 100, 100);
doc.end();
const data = doc.read();
console.log(data.toString("base64"));

I was in a similar predicament, wanting to generate PDF on the fly without having temporary files lying around. My context is a NodeJS API layer (using Express) which is interacted with via a React frontend.

Ironically, a similar discussion for Meteor helped me get to where I needed. Based on that, my solution resembles:

const PDFDocument = require('pdfkit');
const { Base64Encode } = require('base64-stream');

// ...

var doc = new PDFDocument();

// write to PDF

var finalString = ''; // contains the base64 string
var stream = doc.pipe(new Base64Encode());

doc.end(); // will trigger the stream to end

stream.on('data', function(chunk) {
    finalString += chunk;
});

stream.on('end', function() {
    // the stream is at its end, so push the resulting base64 string to the response
    res.json(finalString);
});