JSFiddle - React, Tailwind, and code Playground

JavaScript

function convertMS(ms) {
  var d, h, m, s;
  s = Math.floor(ms / 1000);
  m = Math.floor(s / 60);
  s = s % 60;
  h = Math.floor(m / 60);
  m = m % 60;
  d = Math.floor(h / 24);
  h = h % 24;
  return { d: d, h: h, m: m, s: s };
};

var start_date = 'April 15, 2014';
var end_date = 'April 20, 2014';

var diff = convertMS(Date.parse(end_date) - Date.parse(start_date));

if(diff.d > 1) {
    console.log('The difference is more than one day: it is '  + diff.d + ' days!');
}
else {
  console.log('The difference is just one day and therefore accepted!');
}