JSFiddle - React, Tailwind, and code Playground

HTML

<textarea></textarea>

<ul>
    <li></li>
    <li></li>
    <li></li> 
    <li></li> 
</ul>

JavaScript

$('textarea').keyup(function(e){
    var e, s, l, t = this;
    $(t).val( $(t).val().replace(/\r\n/g, '\r') );
    s = t.selectionStart;
    e = t.selectionEnd;
    l = $(t).val().length;
    $('ul')
        .append('<li>Start = ' + s + ', End = ' + e + ', Length = ' + l + '</li>')
        .find('li:first').remove();
});