(page requirements)

How to display the last modified date

So you want to display the date your page was last modified? It's just a matter of displaying the document.lastModified property in JavaScript, but displaying it in a more user-friendly format is going to take some code.
 
If you're in a hurry, simply copy and paste the following code on to your web page (where you want the last modified date to appear):
 
<script 
  type="text/JavaScript" 
  language="JavaScript">
<!-- 
//
// format date as dd-mmm-yy
// example: 12-Jan-99
//
function date_ddmmmyy(date)
{
  var d = date.getDate();
  var m = date.getMonth() + 1;
  var y = date.getYear();

  // handle different year values 
  // returned by IE and NS in 
  // the year 2000.
  if(y >= 2000)
  {
    y -= 2000;
  }
  if(y >= 100)
  {
    y -= 100;
  }

  // could use splitString() here 
  // but the following method is 
  // more compatible
  var mmm = 
    ( 1==m)?'Jan':( 2==m)?'Feb':(3==m)?'Mar':
    ( 4==m)?'Apr':( 5==m)?'May':(6==m)?'Jun':
    ( 7==m)?'Jul':( 8==m)?'Aug':(9==m)?'Sep':
    (10==m)?'Oct':(11==m)?'Nov':'Dec';

  return "" +
    (d<10?"0"+d:d) + "-" +
    mmm + "-" +
    (y<10?"0"+y:y);
}


//
// get last modified date of the 
// current document.
//
function date_lastmodified()
{
  var lmd = document.lastModified;
  var s   = "Unknown";
  var d1;

  // check if we have a valid date
  // before proceeding
  if(0 != (d1=Date.parse(lmd)))
  {
    s = "" + date_ddmmmyy(new Date(d1));
  }

  return s;
}

//
// finally display the last modified date
// as DD-MMM-YY
//
document.write( 
  "This page was updated on " + 
  date_lastmodified() );

// -->
</script>
Listing #1 : JavaScript code. Download lmd1.htm (0.77 KB).
 
Result:
 
 
 
     How does it work?
 
  • First we check the document.lastModified property for a valid date using "Date.parse()". This check is necessary because some web servers may not return the last modified date. Also, some browsers may suppress this information for security reasons.
     
  • Then we simply call "date_ddmmmyy()" function to format document.lastModified into a more readable date.
 
    NOTE: To get around Year 2000 (Y2K) issues related to the date returned by the document.lastModified property and JavaScript implementations of some browsers, we're displaying the default 2 digit year in this example. Even the "getFullYear()" function used to get the 4 digit year does not work as documented on all browsers when combined with document.lastModified.
 
 
Applicable Keywords : HTML, Internet Explorer, Explorer 3.x, Explorer 4.x, Explorer 5.x, Internet, JavaScript, JavaScript 1.0, JavaScript 1.1, JavaScript 1.2, Netscape Navigator, Navigator 2.x, Navigator 3.x, Communicator 4.x, Netscape 6.x, World Wide Web
 
 
 
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