Since 4.2 the course/format/amd/src/local/content.js has 4 actions that trigger a _reloadCMmmethod:

• Changing visible attribute
• Changing stealth attribute
• Changing activity sectionid
• Changing activity indentation

In some scenarios, a user action can do more than one change, and the _reloadCm is executed twice. This is not a big problem, but it is completely unnecessary.

How to reproduce it in Moodle 4.2:

1. Enable stealth activities
2. Go to a topics format course with some activities
3. Open the browser network monitor and filter connections by "fragment" text
4. Hide one activity
5. Check that the monitor shows one new "fragment" connection
6. Now make available (stealth) the activity
7. Expected: a new "fragment" connection should appear
8. What happens: 2 new "fragment" connections appear, one from the visible attribute and one from the stealth.

Technical shaping

The content._reloadCm method is defined as various watchers in the "getWatcher" method. This is the reason why it is triggered several times. In this case, all cm refresh is centralised in a single method. This complicates the debouncing process because each CM could be refreshed simultaneously, for example, when updated section visibility.

The _reloadCm should use a map of debounced refresh methods to prevent executing unnecessary calls to fragment. One per each CM id.