Entry

How can I base 64 encode a string?

How can I base 64 decode a string?

How can I base 64 encode a form field's value?

Nice example to de-code, but how do you en-code base 64 for IE?

Oct 1st, 2003 20:59
Jeff Wong, Thomas Loo, Louise Tolman, Martin Honnen, jsWalter,

I find that there having problem when I encode chinese char. Here is 
the code change(It work with chinese char)
<script>
var base64s =
 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
function encode(decStr){
decStr=escape(decStr);		//line add for chinese char
  var bits, dual, i = 0, encOut = '';
  while(decStr.length >= i + 3){
    bits =
    (decStr.charCodeAt(i++) & 0xff) <<16 |
    (decStr.charCodeAt(i++) & 0xff) <<8  |
     decStr.charCodeAt(i++) & 0xff;
    encOut +=
     base64s.charAt((bits & 0x00fc0000) >>18) +
     base64s.charAt((bits & 0x0003f000) >>12) +
     base64s.charAt((bits & 0x00000fc0) >> 6) +
     base64s.charAt((bits & 0x0000003f));
    }
  if(decStr.length -i > 0 && decStr.length -i < 3){
    dual = Boolean(decStr.length -i -1);
    bits =
     ((decStr.charCodeAt(i++) & 0xff) <<16) |
     (dual ? (decStr.charCodeAt(i) & 0xff) <<8 : 0);
    encOut +=
      base64s.charAt((bits & 0x00fc0000) >>18) +
      base64s.charAt((bits & 0x0003f000) >>12) +
      (dual ? base64s.charAt((bits & 0x00000fc0) >>6) : '=') +
      '=';
    }
  return encOut
  }
function decode(encStr) {
  var bits, decOut = '', i = 0;
  for(; i<encStr.length; i += 4){
    bits =
     (base64s.indexOf(encStr.charAt(i))    & 0xff) <<18 |
     (base64s.indexOf(encStr.charAt(i +1)) & 0xff) <<12 | 
     (base64s.indexOf(encStr.charAt(i +2)) & 0xff) << 6 |
      base64s.indexOf(encStr.charAt(i +3)) & 0xff;
    decOut += String.fromCharCode(
     (bits & 0xff0000) >>16, (bits & 0xff00) >>8, bits & 0xff);
    }
  if(encStr.charCodeAt(i -2) == 61)
    undecOut=decOut.substring(0, decOut.length -2);
  else if(encStr.charCodeAt(i -1) == 61)
    undecOut=decOut.substring(0, decOut.length -1);
  else undecOut=decOut;
  return unescape(undecOut);		//line add for chinese 
char
  }
var str = "«Y­ø«Y¯u«Ywork¬[<br>\n¦n¦ü¯u«Y±owar";
var enc_str = encode(str);
alert(decode(enc_str));
</script>
Jeff Wong