JSFiddle - React, Tailwind, and code Playground

HTML

<script src="//cdnjs.cloudflare.com/ajax/libs/moment.js/2.5.0/moment.min.js"></script>
<input type="text" id="diff" value="..." />

JavaScript

$( document ).ready(function() {
var t1 = moment("2014-01-21 13:50:20.123", "YYYY-MM-DD HH:mm:ss.sss");

    var t2 = moment("2014-01-21 12:50:20.123", "YYYY-MM-DD HH:mm:ss.sss");

    var diff = t1.diff(t2, 'seconds');

    $("#diff").val(diff);    
});