Chrome not handling chunked responses like Firefox, Safari

I have a test node server that is sending chunked responses every few two seconds with the following headers:

response.setHeader('Content-Type', 'text/plain')
response.setHeader('Transfer-Encoding', 'chunked')

Every two seconds, I write out to the response:

response.write('Hello World');

When I do a curl on the endpoint, I get a chunk back every two seconds:

Hello World
(wait two seconds)
Hello World
(wait two seconds)
Hello World

It works like it's supposed to in curl.

For my Javascript on the client side, I set up a new XMLHttpRequest and assign a function to print out its responseText for the onprogress event. Here is where the implementation seems to differ across browsers.

In Firefox and Safari, I get similar behavior as when I curl. An onprogress event fires for each "Hello World".

In Chrome, an onprogress event fires only when all of chunks have been received and I do a response.end() on the server side. And when I try to print out the responseText, only an empty string prints out.

Here is what the client-side code looks like:

var xhr = new XMLHttpRequest()
xhr.onprogress = function() {
  // Firefox, Safari prints out an accumulation of the chunks
  // Chrome prints out an empty string
  console.log(xhr.responseText);
}