JSFiddle - React, Tailwind, and code Playground

HTML

<div id="demo">
</div>

JavaScript

var oneDay = 24*60*60*1000; // hours*minutes*seconds*milliseconds
   var firstDate = new Date();
   var secondDate = new Date(2016,02,20);
   var diffDays = 'expired';
   if(secondDate>=firstDate){
      diffDays = parseInt((secondDate - firstDate)/oneDay) + ' days left';
   }
   document.getElementById("demo").innerHTML =diffDays;