JSFiddle - React, Tailwind, and code Playground

HTML

<textarea placeholder="press enter"></textarea><br><br>
cache:    <span id="cache"></span><br><br>
textarea: <span id="textareaspan"><!-- shows "\r" --></span><br><br>
span:     <span id="spanspan"><!-- shows "\n" --></span>

JavaScript

$(document).ready(function () {
	$('textarea').keypress(function (e) {
		var c = String.fromCharCode(e.keyCode); // same with e.charCode
		$('#cache').html(c);
		$('#textareaspan').html(c.replace(/\r\n/,'\\r\\n') // windows
   										    	 .replace(/\n\r/,'\\n\\r') // lol wut
   										 	     .replace(/\r/,'\\r')      // mac < 0S9 (!?)
    										     .replace(/\n/,'\\n'));    // mac
    $('#spanspan').html($('#cache').html().replace(/\r\n/,'\\r\\n')
							   										 	    .replace(/\n\r/,'\\n\\r')
    																	    .replace(/\r/,'\\r')
    																	    .replace(/\n/,'\\n'));
	});
});