I have some knowledge in front end and programming in general. I searched for what I'm asking but still confused. I have a site that after some time, it make some appointments (that are exist), active. So I want to make extension(as it is the suitable idea in my head now, feel free to advice me with another one) to refresh the page every some time (1 minute or 5 for example) and detect if there are new appointment becomes available or not. I don't know what class or change they made to make it active, so maybe I'm going to check if the HTML element has changed or not.if changed, alarm maybe run.
Thanks in advance.