Simple boilerplate for experimenting with the new OpenLayers 5.3.0.
git clone https://github.com/tssmits/20190206openlayers.git
Alternatively you can download the repository.
To properly display everything in your browser, you need to serve the html from an http server. You can spin up a server easily if you have PHP installed:
cd src
php -S localhost:1234
Or Python:
cd src
# python 2
python -m SimpleHTTPServer 8000
# python 3
python -m http.server 8000
Then visit http://localhost:1234 in your favorite browser.
Don't have PHP? No fear! See https://gist.github.com/willurd/5720255 for a list of one-liners that start a static server.
Of course, you can also use your LAMP/XAMPP stack or plain old Apache if you have them installed.
Now you should see a simple map in your browser. Edit src/index.html to change the appearance of the map.