JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id="mytextarea" value="hello" name="Message"></textarea>
<div id="charNum"></div>

JavaScript

$('#mytextarea').keyup(function(){          
      var len = $(this).val().length;
      if (len >= 160) {
          var output = $(this).val().substring(0, 160);
          $(this).val(output);
      } else {
          $('#charNum').html(160 - len);
      }
});