How to setup a local testing server

These commands serve the directory where started. In this case, an index.html will be shown in the browser under the provided url from the command:

# If Python version returned above is 3.X
python3 -m http.server

# On windows try "python" instead of "python3"
# If Python version returned above is 2.X
python -m SimpleHTTPServer

Source:

How do you set up a local testing server?
Throughout most of the learning area, we tell you to just open your examples directly in a browser — this can be done by double clicking the HTML file, dragging and dropping it into the browser window, or choosing File Open... and navigating to the HTML file. There are many ways to achieve this.