JSFiddle - React, Tailwind, and code Playground
HTML
<textarea id="t">Line 1
Line 2</textarea>
<p id='T'></p>
<p id='p1'></p>
<p id='p2'></p>
<p id='p3'></p>
JavaScript
T.innerText = "Position of LF: "+ t.value.indexOf("\n");
p1.innerHTML = t.value;
p2.innerHTML = t.value.replace("\n", "<br/>");
p3.innerText = t.value.replace("\n", "<br/>");