JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container"></div>

CSS

.trans {
    width: 20px;
    height: 20px;
    background-color: cyan;
    -webkit-transition: all 5s ease;
       -moz-transition: all 5s ease;
        -ie-transition: all 5s ease;
         -o-transition: all 5s ease;
            transition: all 5s ease;
}

JavaScript

var div = $('<div class="trans" />');
$('#container').append(div);

var div = $('<div />').addClass('trans');
    $('#container').append(div);
    div.css('width');//add this line
    div.css('width', '200px');