Tell User If Document Has Been Modified Since Last Visit

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This shows how to have an HTML page know to tell the user if the page has been modified since that users last visit.

Body Code:

<script type=text/javascript>

function getCookieVal (offset) {
  var endstr = document.cookie.indexOf (";", offset);
  if (endstr == -1)
    endstr = document.cookie.length;
  return unescape(document.cookie.substring(offset, endstr));
}

function GetCookie (name) {
  var arg = name + "=";
  var alen = arg.length;
  var clen = document.cookie.length;
  var i = 0;
  while (i < clen) {
    var j = i + alen;
    if (document.cookie.substring(i, j) == arg)
      return getCookieVal (j);
    i = document.cookie.indexOf(" ", i) + 1;
    if (i == 0) break; 
  }
  return null;
}

function SetCookie (name, value) {
  var argv = SetCookie.arguments;

  var argc = SetCookie.arguments.length;

  var expires = (argc > 2) ? argv[2] : null;
  var path = (argc > 3) ? argv[3] : null;
  var domain = (argc > 4) ? argv[4] : null;
  var secure = (argc > 5) ? argv[5] : false;
  document.cookie = name + "=" + escape (value) +
    ((expires == null) ? "" : ("; expires=" + expires.toGMTString())) +
    ((path == null) ? "" : ("; path=" + path)) +
    ((domain == null) ? "" : ("; domain=" + domain)) +
    ((secure == true) ? "; secure" : "");
}

function DeleteCookie(name) {
  var exp = new Date();
  FixCookieDate (exp);
  exp.setTime (exp.getTime() - 1);
  var cval = GetCookie (name);
  if (cval != null)
    document.cookie = name + "=" + cval + "; expires=" + exp.toGMTString();
}

var cookie_date=new Date(document.lastModified);
var expdate = new Date();
expdate.setTime(expdate.getTime()+(5*24*60*60*1000)); // 5 days

document.write("This page last updated on: "+document.lastModified);
document.write("<br>");
if (!(cookie_date == GetCookie("cookie_date"))){
  SetCookie("cookie_date",cookie_date,expdate);
  document.write("<font color='blue'>This page has changed since your last visit!</font><br>");
}

</script>

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