JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://meetselva.github.io/attrchange/javascripts/attrchange.js"></script>
<div id="test">
  test
</div>
<div id="logger">
  test 2
</div>

CSS

#test, #logger {
    padding: 10px 10px;
    width: 100px;
    float: left
}

#test {  
  height: 100px;
}

.border-left {
  border-left: 1px solid black;
}

.border-right {
  border-right: 1px solid black;
}

JavaScript

$(function () {
    var prevHeight = $('#test').height();
    $('#logger').attrchange({
        callback: function (e) {
            var curHeight = $(this).height();            
            if (curHeight > prevHeight) {
            console.log('greater');
               $(this).addClass('border-left');
               $('#test').removeClass('border-right','');
            }else {
               $(this).removeClass('border-left');
               $('#test').addClass('border-right');
            }      
        }
    }).resizable();
});