Email Decoder Source Code (decodeEmail.js)

//
// $Id: decodeEmail.js,v 1.3 2008/11/06 21:05:28 pwh Exp $
//
// A script to decode email addresses that were scrambled to hide them from
// spam-bots.
//


function binSort ( indices, text )

{
   var bins = new Array ()
   var length = indices.length
   var base = 0
   var newIndices = new Array ()

   for ( var i = 0; i < 256; ++i ) bins [i] = 0

   for ( var i = 0; i < length; ++i ) {

	var j = text.charCodeAt ( indices [i] )

	bins [j] += 1
   }

   for ( var i = 0; i < 256; ++i ) {

	var inc = bins [i]

	bins [i] = base

	base += inc
   }

   for ( var i = 0; i < length; ++i ) {

	var j = text.charCodeAt ( i )
	var k = bins [j]

	++bins [j]
	newIndices [k] = i
   }

   return ( newIndices )
}


function bwtDecode ( cipher )

{
   var code = ""
   var plainText = ""
   var length = cipher.length
   var indices = new Array ()
   var key = 0
   var i = 0
   var j = 0

   while ( i < length ) {

	var ch = cipher.charAt ( i )

	if ( ch != " " && ch != "\t" && ch != "\n" && ch != "\r" ) {

		indices [j] = j
		code += ch
		++j

	} else if ( ! key ) key = j

	++i
   }

   length = j

   if ( key == length ) key = 0

   if ( length > 0 ) {

	indices = binSort ( indices, code )

	j = key

	while ( length-- > 0 ) {

		var ch

		j = indices [j]

		ch = code.charAt ( j )

		if ( ch == "\\" && length-- > 0 ) {

			j = indices [j]

			ch = code.charAt ( j )

			switch ( ch ) {

			  case "r":

				ch = "\r"
				break

			  case "n":

				ch = "\n"
				break

			  case "s":

				ch = " "
				break

			  case "t":

				ch = "\t"
				break

			  case "x":

				var digits = length
				var chCode = 0

				if ( digits > 2 ) digits = 2

				while ( digits-- > 0 ) {

					var littleA = "a".charCodeAt (0)
					var bigA = "A".charCodeAt (0)

					--length
					j = indices [j]
					ch = code.charCodeAt ( j )

					if ( ch > littleA ) ch
							-= ( littleA - 10 )
					else if ( ch > bigA ) ch
							-= ( bigA - 10 )
					else ch -= "0".charCodeAt (0)

					chCode *= 16
					chCode += ch
				}

				ch = String.fromCharCode ( chCode )

				break;
			}
		}

		plainText += ch
	}
   }

   return ( plainText )
}


function decodeEntities ( htmlText )

{
   var text = ""
   var length = htmlText.length
   var i = 0

   while ( i < length ) {

	var ch = htmlText.charAt ( i++ )

	if ( ch == "&" ) {

		var remainder = length - i

		if ( remainder > 3
			&& htmlText.substring ( i, i + 4 ) == "amp;" ) i += 4

		else if ( remainder > 2 ) {

			switch ( htmlText.substring ( i, i + 3 ) ) {

			  case "gt;":

				ch = ">"
				i += 3
				break

			  case "lt;":

				ch = "<"
				i += 3
				break
			}
		}
	}

	text += ch
   }

   return ( text )
}


function useHTMLentities ( text )

{
   var htmlText = ""
   var length = text.length
   var i = 0

   while ( i < length ) {

	var ch = text.charAt ( i++ )

	switch ( ch ) {

	  case "&":

		htmlText += "&amp;"
		break

	  case "<":

		htmlText += "&lt;"
		break

	  case ">":

		htmlText += "&gt;"
		break

	  default:

		htmlText += ch
		break
	}
   }

   return ( htmlText )
}


function decodeEmail ()

{
   var addresses = document.getElementsByName ( "e_mail" )
   var length = addresses.length
   var i

   for ( i = 0; i < length; i++ ) {

	if ( addresses [i].href == "mailto:" ) {

		var address
		= bwtDecode ( decodeEntities ( addresses [i].innerHTML ) )

		addresses [i].href += address
		addresses [i].innerHTML = useHTMLentities ( address )
	}
   }
}