Express.js - how to download base64 string as PDF file?

base64, express, file, node.js, stream

Solution

I ended up to decode the pdf first and then send it to the browser as binary as follows:

(For simplicity I use `node-http` here but the functions are available in `express` as well)

const http = require('http');

http
  .createServer(function(req, res) {
    getEncodedPDF(function(encodedPDF) {
      res.writeHead(200, {
        'Content-Type': 'application/pdf',
        'Content-Disposition': 'attachment; filename="filename.pdf"'
      });

      const download = Buffer.from(encodedPDF.toString('utf-8'), 'base64');

      res.end(download);
    });
  })
  .listen(1337);

What drove me nuts here was the testing with Postman: I was using the Send Button instead of the Send and Download Button to submit the request:

Using the Send button for this request causes that the pdf file becomes corrupted after saving.

Problem

I have pdf file encoded as base64 string. How to download this string to the browser as file in .pdf format? What I have already tried: ``` res.set('Content-Disposition', 'attachment; filename="filename.pdf"'); res.set('Content-Type', 'application/pdf'); res.write(fileBase64String, 'base64'); ```

Original source