JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id="textarea"></textarea>
<br>
<input type="text" id="input"></input>

JavaScript

$("#input , #textarea").on('input', function(evt) {
			  var input = $(this);
			  var start = input[0].selectionStart;
			  $(this).val(function (_, val) {
			    return val.toUpperCase();
			  });
			  input[0].selectionStart = input[0].selectionEnd = start;
			});