function URLEncode(plaintext) {
	var encoded = "";
	var CONVERTCHARS = "+&?";
	var HEX = "0123456789ABCDEF";
	for (var i = 0; i < plaintext.length; i++ ) {
		var ch = plaintext.charAt(i);
		if (CONVERTCHARS.indexOf(ch) != -1 ) {
		    var charCode = ch.charCodeAt(0);
			encoded += "%";
			encoded += HEX.charAt((charCode >> 4) & 0xF);
			encoded += HEX.charAt(charCode & 0xF);
		} else {
			 encoded += ch;
		}
	}
	return encoded;

};

function URLDecode(encoded)
{
   // Replace + with ' '
   // Replace %xx with equivalent character
   // Put [ERROR] in output if %xx is invalid.
   var HEXCHARS = "0123456789ABCDEFabcdef"; 
   var plaintext = "";
   var i = 0;
   while (i < encoded.length) {
       var ch = encoded.charAt(i);
	   if (ch == "+") {
	       plaintext += " ";
		   i++;
	   } else if (ch == "%") {
			if (i < (encoded.length-2) 
					&& HEXCHARS.indexOf(encoded.charAt(i+1)) != -1 
					&& HEXCHARS.indexOf(encoded.charAt(i+2)) != -1 ) {
				plaintext += unescape( encoded.substr(i,3) );
				i += 3;
			} else {
				alert( 'Bad escape combination near ...' + encoded.substr(i) );
				plaintext += "%[ERROR]";
				i++;
			}
		} else {
		   plaintext += ch;
		   i++;
		}
	} // while
   return plaintext;
};