Webdesign

/* Back to parent directory button -  
	
	If the current file is either "index.*" or the default file in a directory,
	then this link points to the parent directory.
	
	If the current file is anything else, it points to the default file 
	(typically index.htm) in the current directory
	
*/

// Get URL and convert to lower case
var DocumentURL=location.href.toLowerCase();

// Get everything after the final /
var DocumentShortName = (DocumentURL.substring( DocumentURL.lastIndexOf("/")+1));

// Get everything before the .
DocumentShortName = DocumentShortName.substring(0,DocumentShortName.lastIndexOf("."))

// Decide whether to use the current or the parent directory as a suitable link 
var LinkBackURL;
if ((DocumentShortName == "index") || (DocumentShortName == ""))
{
	LinkBackURL =  "../";
}
else
{
	LinkBackURL =  "./";
}

// Display HTML to implement this link
document.writeln ('<p> <a href="' + LinkBackURL + '"> Back to index</a> '); 

// See it work by clicking the link below