I'm trying to run some javascript in my html documentation. To test this I created a very simple index.html and simple.qhp , generating a .qch with qhelpgenerator simple.qhp -o simple.qch and visualizing it using qtAssistant. The body of index.html looks like this :

 <p>Hi there, today's the <span id="demo"></span> !</p>
 <script>
     document.getElementById("demo").innerHtml = new Date();
 </script>

The strange thing is that it's working fine on Arch but not on KDENeon (using system Qt5 installed via pacman/apt). Both Qt version are 5.12.2. Is it because the 2 releases do not ship the same features or is there something else ?

[Update]
So I tested using the release version 5.12.2 from qt website (both offline and online) on KDENeon and Windows and it's not working either.
So the question would actually be : is QHelper supposed to support JavaScript ? That would mean Arch's QAssistant executing JS would be a bug.
[Update2]
QAssistant seems to be the key since Arch's QAssistant can read the .qch file generated by any of mentioned version of qhelpgenerator