Empty req.body receiving text/plain POST request to node.js

Summarising the above comments which answer the question:

• The client's XMLHttpRequest is correct
• On the server side, Express uses connect's bodyParser which by default only supports the following content types:
  • application/json
  • application/x-www-form-urlencoded
  • multipart/form-data
• Because the content-type of text/plain is not implemented by Express, there is no method to wait for the body to be received before calling the app/post route.
• The solution is to add the text/plain content type to Express as described here

Add

app.use(express.text())

You can read more about it here