function URLDecode(url) //function decode URL
{
// Replace + with ' '
// Replace %xx with equivalent character
// Put [ERROR] in output if %xx is invalid.
var HEXCHARS = "0123456789ABCDEFabcdef";
var encoded = url;
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;
};