Chrome Version       : 54.0.2820.2
URLs (if applicable) : https://github.com/ericandrewlewis/duplicate-ajax-request-in-the-browser/
Other browsers tested:
  Add OK or FAIL, along with the version, after other browsers where you
have tested this issue:
     Safari: FAIL 9.1.1
    Firefox: FAIL 46.0.1
         IE:

What steps will reproduce the problem?

I've created a repository with a basic Node.js server to illustrate the problem: https://github.com/ericandrewlewis/duplicate-ajax-request-in-the-browser/

Clone this repository, run `node index.js`. Open a browser and load `http://localhost:3000`. Open DevTools and look at the Network pane, and compare it to the Node server's log.

What is the expected result?

Only one request is displayed in DevTools Network pane, so I would expect only one request received by the server.

What happens instead?

The server receives one HTTP request, and then a duplicate after 3 seconds.


Please provide any additional information below. Attach a screenshot if
possible.

This may be related to HTTP/1.1 RFC 8.2.4 (http://stackoverflow.com/questions/14302512/what-happens-when-no-response-is-received-for-a-request-im-seeing-retries/14345476#14345476). I'm not sure Chromium's implementation is to spec. eg. An HTTP GET request does not include a request body.

If this behavior is intentional, it would be useful to surface the fact that a duplicate request is sent to the user in the DevTools Network pane.