JSFiddle - React, Tailwind, and code Playground

JavaScript

var totalDays = 0;
var oneDay = 24*60*60*1000; 
var startDate = new Date('8/12/2012');
var endDate = new Date('8/25/2012');
var startTime = startDate.getTime();
var endTime = endDate.getTime();

var DaysArr = new Array("Sunday","monday","tuesday","Wednesday","Thursday","Friday","Saturday");
for(loopTime = startTime; loopTime <= endTime; loopTime += oneDay)
{
  var loopDay=new Date(loopTime);
    var day = loopDay.getDay();
    if(day != 0 && day != 6) totalDays++;
}
document.write(totalDays);