Debugging on how this comes to exists later, I see that it is put into a jQuery Deferred Promise by the “EXPAND ALL” “collapsemenu” component when the require “core_form/collapsesections” is called. Unfortunately this promise is not accessible at global level or even at the moment of the “Before BODY” section, this has not been created yet. Oh well, that should had been an easy solution by just adding an extra “.then” callback to the promise.

Back to the drawing board. I didn’t want to put an ugly setTimeout (I know that will work). I wanted to put my own promise or event that will tell me when the collapse Elements are available and ready. I looked into the last things “collapsesections” does. It collects all the collapse Elements ids and put them into the attribute “aria-controls”. So, I see that I could use a MutationObserver that when an attribute is modified, it will trigger a callback and everything is ready. So I ended with code like this:

if (document.getElementById(‘page-login-signup’) || document.getElementById(‘page-user-editadvanced’)) {
const observer = new MutationObserver(() => {
document.querySelector(‘#collapseElement-4’).click();
document.querySelector(‘#collapseElement-5).click();
observer.disconnect();
});
observer.observe(document.querySelector(‘.collapsemenu’), {attributeFilter: [‘aria-controls’]});
}

I simplified the full MutationObserver formal callback as I do not need to iterate on the records and I do not need to check which attribute mutated as I filtered to observe only one.

I hope this save hours of frustration to anybody else with the same problem. Maybe you could improve your article, as it is referred on the Moodle documentation.