Ask Ben: Cleaning Two Digit Years Using Javascript And Regular Expressions

code-1.js

// This takes a date string that MIGHT have a two digit year
// as the last two digits. If it does, this function replaces
// the two digit year with what it *assumes* is the proper
// four digit year.
function CleanDate( strDate ){

	// Return the cleaned date.
	return(
		strDate.replace(

			// This regular expression will search for a slash
			// followed by EXACTLY two digits at the end of
			// this date string. The two digits are being
			// grouped together for future referencing.
			new RegExp( "/(\\d{2})$", "" ),

			// We are going to pass the match made by the
			// regular expression off to this function literal.
			// Our arguments are as follows:
			// $0 : The entire match found.
			// $1 : The first group within the match.
			function( $0, $1 ){

				// Check to see if our first group begins with
				// a zero or a one. If so, replace with 20 else
				// replace with 19.
				if ($1.match( new RegExp( "^[01]{1}", "" ) )){

					// Replace with 20.
					return( "/20" + $1 );

				} else {

					// Replace with 19.
					return( "/19" + $1 );

				}

			}
			)
		);

}