You can create text-nodes and use css to format the text without using
<br> tags. If this works for your project just do something like:
stylesheet-excerpt:
p{white-space

re;}
script-excerpt:
document.getElementsByTagName('p')[0].appendChild(
document.createTextNode( document.feedbackneu.nachricht.value )
);
To do the replacement you'll need to cover all the possible newline
interpretations--and this varies by OS/encoding/browser (maybe other
possibilities too). See
http://en.wikipedia.org/wiki/Newline
You could try something like:
var MyString = document.feedbackneu.nachricht.value
MyString.replace(/\n/g,"\n<br />");
document.getElementById('ausgabeX').innerHTML = MeinString;