What are the possible approaches to create a changes tracker in javascript?

How to create a text change tracker that detect and shows the deleted text and the new text and all the change. The following example from apple pages.
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Also, I think you are familiar with github change tracker where it highlights the new text in green the the removed text in red...

• Goal I want to create a document app like pages that track the changes and changes history to store it in the DB and show it in the frontend.