JSFiddle - React, Tailwind, and code Playground

JavaScript

var startdate = new Date("2015-07-04T00:00:00");
var enddate = new Date("2015-07-11T23:59:59");

var timeDifference  = Math.abs(enddate.getTime() - startdate.getTime());
var differenceDays = Math.ceil(timeDifference  / (1000 * 3600 * 24));  //return 8

  if (differenceDays > 7){
    alert('set timeFormat = "30days"');
}else{
    alert('set timeFormat = "7days"');
}