Convert a readable stream to base64 string

streamToBase64.js

/**
 * Convert a Readable Stream to base64 string
 * @param {ReadableStream} stream - a readable stream to convert in base64 string
 * @returns {Promise} - Promise that resolve in a string containing the base64
 */
const streamToBase64 = (stream) => {
  const concat = require('concat-stream')
  const { Base64Encode } = require('base64-stream')

  return new Promise((resolve, reject) => {
    const base64 = new Base64Encode()

    const cbConcat = (base64) => {
      resolve(base64)
    }

    stream
      .pipe(base64)
      .pipe(concat(cbConcat))
      .on('error', (error) => {
        reject(error)
      })
  })
}

// Example: https://repl.it/@luan0ap/streamToBase64