We will use a small web site that is included in the www folder of the sample code. To follow along, start a web server from within the www folder. This can be done with Python 3 as follows:
www $ python3 -m http.server 8080Serving HTTP on 0.0.0.0 port 8080 (http://0.0.0.0:8080/) ...
The DOM of a web page can be examined in Chrome by right-clicking the page and selecting Inspect. This opens the Chrome Developer Tools. Open a browser page to http://localhost:8080/planets.html. Within chrome you can right click and select 'inspect' to open developer tools (other browsers have similar tools).
This ...