How to read form fields before the file in a multipart upload

busboy-fields-before-file.js

// NOTE: this only works if the file upload form field appears last

const busboy = require('connect-busboy');
const express = require('express');

const app = express();

app.use(busboy());

app.post('/upload', (req, res) => {
    if (req.busboy) {
        req.busboy.on('field', (fieldName, fieldVal) => {
            req.pause(); // pause the request stream while we do something with this field

            // Do whatever
            console.log(`${fieldName}: ${fieldVal}`);

            // Simulate a long running task to do before resuming the request stream
            for (let n = 0; n < 1000000000; ) { n += 1 }
            
            req.resume(); // resume the request stream once we are done here
        });

        req.busboy.on('file', (fieldName, fileStream, fileName, encoding, mimeType) => {
            console.log(`file: ${fileName}`);
            fileStream.pipe(res);
        });

        req.pipe(req.busboy);
    } else {
        res.send('No file');
    }
});

app.listen(6060, () => console.log('serving...'));