urlencode urldecode

//urlencode
function URLEncode(txt)
{
 // The Javascript escape and unescape functions do not correspond
 // with what browsers actually do...
 var SAFECHARS = "0123456789" +     // Numeric
     "ABCDEFGHIJKLMNOPQRSTUVWXYZ" + // Alphabetic
     "abcdefghijklmnopqrstuvwxyz" +
     "-_.!~*"()";     // RFC2396 Mark characters
 var HEX = "0123456789ABCDEF";

 var plaintext = txt;
 var encoded = "";
 for (var i = 0; i < plaintext.length; i++ ) {
  var ch = plaintext.charAt(i);
     if (ch == " ") {
      encoded += "+";    // x-www-urlencoded, rather than %20
  } else if (SAFECHARS.indexOf(ch) != -1) {
      encoded += ch;
  } else {
      var charCode = ch.charCodeAt(0);
   if (charCode > 255) {
       alert( "Unicode Character ""
                        + ch
                        + "" cannot be encoded using standard URL encoding.n" +
              "(URL encoding only supports 8-bit characters.)n" +
        "A space (+) will be substituted." );
    encoded += "+";
   } else {
    encoded += "%";
    encoded += HEX.charAt((charCode >> 4) & 0xF);
    encoded += HEX.charAt(charCode & 0xF);
   }
  }
 } // for

 return encoded;
};

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