How to make use of it:

1. Include the autoResize.js plugin after loading the newest jQuery library.

<script src="/path/to/cdn/jquery.slim.min.js"></script>
<script src="/path/to/Jquery.autoResize.js"></script>

2. Or instantly insert the next JS snippets into your undertaking.

$.fn.autoResize = function(){
  let r = e => {
    e.style.height = '';
    e.style.height = e.scrollHeight + 'px'
  };
  return this.each((i,e) => {
    e.style.overflow = 'hidden';
    r(e);
    $(e).bind('input', e => {
      r(e.target);
    })
  })
};

3. Call the function autoResize in your textarea and performed it.

$('textarea').autoResize();

Auto Stretch Textarea To Fit Its Content, autoResize Plugin/Github

See Demo And Download