How to display the last modified date

bholas · #1 08-10-2010, 03:04 PM

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>

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.

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.

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How to display the last modified date

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