<!-- Paste this code into an external JavaScript file named: dateDiff.js  -->

/* This script and many more are available free online at
The JavaScript Source :: http://javascript.internet.com
Created by: JavaScript Demos :: http://www.javascript-demos.com/ */

function calcDays(){
  var dateA = document.getElementById('delivery-date').value;
  var dateB = document.getElementById('start-date').value;
  var dateC = document.getElementById('end-date').value;
  var dateD = document.getElementById('return-date').value;
  
  if (dateA != "" && dateB != "" && dateB != "" && dateB != "")
  {
  
    dateA = dateA.split("/");
    dateB = dateB.split("/");
    dateC = dateC.split("/");
    dateD = dateD.split("/");
  
    var aDate = new Date(dateA[1]+"/"+dateA[0]+"/"+dateA[2]);
    var bDate = new Date(dateB[1]+"/"+dateB[0]+"/"+dateB[2]);
    var cDate = new Date(dateC[1]+"/"+dateC[0]+"/"+dateC[2]);
    var dDate = new Date(dateD[1]+"/"+dateD[0]+"/"+dateD[2]);
  
  
    var daysOut = Math.abs(Math.round((dDate-aDate)/86400000));
    var daysCharged = Math.abs(Math.round((cDate-bDate)/86400000));
  
    document.getElementById('No_of_days_out').value = daysOut;
    document.getElementById('No_of_days_charged').value = daysCharged;
  }
}