Electron blob to buffer, I made this to use with the nativeImage class.

blob_to_buffer.js

function blob_to_buffer(blob, callback) {
  // Create a file reader instance.
  const file_reader = new FileReader()

  // Listen to when reading is finished and 
  // run the callback with a buffer.
  file_reader.addEventListener("loadend", event => {
    if (event.error) {
      callback(event.error)
    }
    else {
      callback(null, new Buffer(file_reader.result))
    }
    
    // Remove the listener.
    file_reader.removeEventListener("loadend", blob_to_buffer, false)
  }, false)

  // Read the blob as a typed array.
  file_reader.readAsArrayBuffer(blob)
  
  return file_reader
}

Blob has an arrayBuffer method now

blob.arrayBuffer()

which returns an array buffer directly