Many thanks for your help.
I have finally understood the problem … and a simple solution is to set “async:false” (I modified the “index.htm” in my first post here so that it can be “successfully re-used”):
$.ajax({
async: false,
Note: this generates a harmless “Web Console” output warning: “Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user’s experience. For more help http://xhr.spec.whatwg.org/”
I didn’t want to modify the “module part” as this is something specific to the current JSROOT version (so it may change in the future, and then I would again need to fight with my custom modifications).