This is a custom Angular 9 demo element. See my website page for more.
If you inspect the source code of this page, you will just find the custom element markup (and the link to its Javascript code):
<app-abacus initial-text="non est unius una sententia"></app-abacus>
Currently, the custom element file is about 238 KB. The whole functionality and its infrastructure are all enclosed.
Type a short text and see the resulting abacus. Additionally, you can change the start and end color for the background gradient.
Note that not all the browsers yet support this custom element. Please use a modern browser (ES6).