Why does Node.js Postgres Wiki example insert multiple records per http request?

Question

We are using the node-postgres (pg on NPM) for our app but were having issues so we decided to go back to the examples on the Wiki:

https://github.com/brianc/node-postgres/wiki/Example

When we run the example, each http request inserts two records into the Postgres ("visit") table. Is this the desired behaviour...?

We published the example code to Heroku: https://node-postgres-example.herokuapp.com
(Note: Visit using Google Chrome)

Note: we made 3 changes to the server.js code from the Wiki to make it run on Heroku this is on GitHub: https://github.com/dwyl/postgres-connection-pool-test

(the changes we made to server.js are purely to (1) create the visit table if it does not already exist, (2) to get the postgres connection string from process.env.DATABSE_URL and (3) to listen on process.env.PORT on Heroku. all the rest of the code is as per the Wiki example)

Answer 1

Your client (browser) seems to make two requests. If you use curl from the command line, the example works as advertised and returns a continuous visit counter:

→ curl -i https://node-postgres-example.herokuapp.com/
HTTP/1.1 200 OK
Server: Cowboy
Connection: keep-alive
Content-Type: text/plain
Date: Sun, 13 Mar 2016 14:19:42 GMT
Transfer-Encoding: chunked
Via: 1.1 vegur

You are visitor number 40

→ curl -i https://node-postgres-example.herokuapp.com/
HTTP/1.1 200 OK
Server: Cowboy
Connection: keep-alive
Content-Type: text/plain
Date: Sun, 13 Mar 2016 14:20:00 GMT
Transfer-Encoding: chunked
Via: 1.1 vegur

You are visitor number 41

Answer 2

The second request is almost certainly the browser requesting /favicon.ico which is an anomaly in the web tech stack in that it's a request the browser makes implicitly without an explicit reference in some containing HTML document. If you handle the favicon request separately, perhaps using express-favicon, you will resolve your issue and only log 1 visit per page load.