While testing this on IE, I noticed that the data is being sent and processed by the server successfully and that the problem is on the clients handling of the server response.
So I researched about this and found out that IE had some issues with `XMLHttpRequest` support and that it used to use its own technology to handle these types of requests, `ActiveX Object`. This issue was with IE7 and below browsers, and I am using IE11, so not sure if this is still relevant.
I am also not sure if this is what's causing the issue in my case but I feel it is close.
StimulusJS Not Serious on Supporting Internet Explorer
Who cares about IE, it is getting killed by Microsoft over Edge so maybe the team that is responsible for StimulusJS are not interested in fully supporting IE. This is just an opinion, as their is still a huge chance that it was my code that caused all this and that StimulusJS fully supports IE in reality.
Also, maybe this is just a pending issue since StimulusJS is new and still being developed.
Who Cares About Internet Explorer
I have read about this recently. Even with all the issues in IE it is still one of the most used browser today.
Not just for going to Mozilla and Chrome's download page but according to this another article from Medium, about the most popular desktop browsers for 2018, it has much more users than Safari, when IE users are combined with Edge.
Back to the code and to the issue of the feature. I dropped the use of StimulusJS for the AJAX functionalities of the commenting forms, I still use it on other functionalities that does not have problems on IE, and reverted to Rails' very own UJS.
Tested the feature again in IE11 and its now working well.