Loader Icon to be added in Angular app

Making my question more descriptive:

I have an app made in Angular 2+ & Gojs and this app has certain nodes made using the Basic Chart type.

I want to add a spinner like this:https://www.w3schools.com/howto/howto_css_loader.asp
to this page before all the nodes load completely.

How can I achieve this?

Thanks Walter

This question does not involve GoJS.