How to do it...

We simply have to set the NODE_DEBUG environment variable to one or more of the supported flags.

Let's start with the timer flag by running our app like so:

$ NODE_DEBUG=timer node index.js

This should show something like the following screenshot:

Let's try running the process again with both timer and http flags enabled:

$ NODE_DEBUG=timer,http node index.js

Now we need to trigger some HTTP operations to get any meaningful output, so let's send a request to the HTTP server using curl (or an alternative method, such as navigating to http://localhost:3000 in the browser):

$ curl http://localhost:3000

This should give output similar to the following screenshot: