Right now I have a hard-ish to read HTML page composed of ~300 lines of code. Most of the code however comes from the same form repeated multiple times, with no changes whatsoever except for the id (which differs by a number). Would it be an acceptable or even encouraged practice to use Javascript to attach the same piece of HTML code to the DOM as many times as I need it? I'm a beginner to JS, so I don't have any clue about any performance impact that this could cause, and I can't see anything bad coming from this approach.
In my opinion, semantic HTML that is verbose and not rendered through JavaScript is the way to go. The only reason you wouldn't want to do this is if your application could scale and more forms would be rendered in the future. If there are a set amount of forms, debugging and handling data will be easiest by simply hardcoding all of the HTML.