progress bar - Documentation on browser built-in page loading indicator

Question

I am trying to find out where there is documentation for common browsers about their built-in page loading indictor. When I do any searches, I find a huge number of articles about how to add such an indicator to your web page. I am not looking for that--rather an explanation of the different built-in approaches used by browsers.

Very often the browser seems to show something in the tab for the page.

For example, on Chrome, there is a spinner at the left to the tab, as shown here:

You can see part of a blue semi-circle surrounding the letters "RH".

Some observations:

1. As stated above, Chrome has a spinner at the left of the tab.
2. Brave is the same as Chrome.
3. Firefox has a color band that moves across the tab.
4. Edge has a spinner with dots at the left of the tab.
5. Safari has a horizontal progress bar that moves under the address bar.

question from:https://stackoverflow.com/questions/65853403/documentation-on-browser-built-in-page-loading-indicator

Answer 1

Waitting for answers