Is rn invisible?

Is rn invisible? In Notepad, when we press enter, the text will wrap the line. is rn invisible? How do we match? Just like the question of editing, how does one implement a line break after a break? ------ Solution ------------------ js control, such as Demo: HTMLcode & lt; html & gt; & lt; head & gt; & lt; is \ r \ n invisible to scr?
In Notepad, when we press enter, the text will wrap the line. is \ r \ n invisible?
How do we match?
Just like the question of editing, how does one implement a line break after a break?

------ Solution --------------------
Js-controlled, like this:
Demo:

HTML code