how to encode/decode ascii85 in javascript

Question

I was looking for an alternative to Base64 which works fine on Unicode characters. I have found ASCII85 which works great however I found no code or command doing that in JS.

I just found this link which does not work for international characters and does not include decode function.

Here there are online Decoder/Encoder.

Even found codes in C language doing that(I don't have enough JS data handling knowledge to convert).

And some codes that I don't know how to run.

I have heard that JQuery does support Base64 but it seems that it does not support Ascii85.

Does somebody know anything about Ascii85 in JS which might help?

thanks

Answer 1

Pure JavaScript Ascii85 AKA Base85 encoding/decoding functions:

function encode_ascii85(a) {
  var b, c, d, e, f, g, h, i, j, k;
  for (!/[^\x00-\xFF]/.test(a), b = "\x00\x00\x00\x00".slice(a.length % 4 || 4), a += b, 
  c = [], d = 0, e = a.length; e > d; d += 4) f = (a.charCodeAt(d) << 24) + (a.charCodeAt(d + 1) << 16) + (a.charCodeAt(d + 2) << 8) + a.charCodeAt(d + 3), 
  0 !== f ? (k = f % 85, f = (f - k) / 85, j = f % 85, f = (f - j) / 85, i = f % 85, 
  f = (f - i) / 85, h = f % 85, f = (f - h) / 85, g = f % 85, c.push(g + 33, h + 33, i + 33, j + 33, k + 33)) :c.push(122);
  return function(a, b) {
    for (var c = b; c > 0; c--) a.pop();
  }(c, b.length), "<~" + String.fromCharCode.apply(String, c) + "~>";
}

function decode_ascii85(a) {
  var c, d, e, f, g, h = String, l = "length", w = 255, x = "charCodeAt", y = "slice", z = "replace";
  for ("<~" === a[y](0, 2) && "~>" === a[y](-2), a = a[y](2, -2)[z](/\s/g, "")[z]("z", "!!!!!"), 
  c = "uuuuu"[y](a[l] % 5 || 5), a += c, e = [], f = 0, g = a[l]; g > f; f += 5) d = 52200625 * (a[x](f) - 33) + 614125 * (a[x](f + 1) - 33) + 7225 * (a[x](f + 2) - 33) + 85 * (a[x](f + 3) - 33) + (a[x](f + 4) - 33), 
  e.push(w & d >> 24, w & d >> 16, w & d >> 8, w & d);
  return function(a, b) {
    for (var c = b; c > 0; c--) a.pop();
  }(e, c[l]), h.fromCharCode.apply(h, e);
}

var myString='This is a test!';
var encoded=encode_ascii85(myString);
var decoded=decode_ascii85(encoded);
document.write(decoded);

Answer 2

using dojo.js framework :

Decode Example + source

Encode Example + source

ascii85 Encoding using

summary:

dojo.require("dojox.encoding.ascii85");
var dc = dojox.encoding
var buf = dc.ascii85.decode("")
var a85 = dc.ascii85.encode("");

Answer 3

You can use my JavaScript ASCII85 (Base85) implementation which can work both with byte arrays and strings