https://www.browardclerk.org/Web2/Scripts/base64.js

1;(function () {
2
3  var object = typeof exports != 'undefined' ? exports : this; // #8: web workers
4  var chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
5
6  function InvalidCharacterError(message) {
7    this.message = message;
8  }
9  InvalidCharacterError.prototype = new Error;
10  InvalidCharacterError.prototype.name = 'InvalidCharacterError';
11
12  // encoder
13  // [https://gist.github.com/999166] by [https://github.com/nignag]
14  object.btoa || (
15  object.btoa = function (input) {
16    var str = String(input);
17    for (
18      // initialize result and counter
19      var block, charCode, idx = 0, map = chars, output = '';
20      // if the next str index does not exist:
21      //   change the mapping table to "="
22      //   check if d has no fractional digits
23      str.charAt(idx | 0) || (map = '=', idx % 1);
24      // "8 - idx % 1 * 8" generates the sequence 2, 4, 6, 8
25      output += map.charAt(63 & block >> 8 - idx % 1 * 8)
26    ) {
27      charCode = str.charCodeAt(idx += 3/4);
28      if (charCode > 0xFF) {
29        throw new InvalidCharacterError("'btoa' failed: The string to be encoded contains characters outside of the Latin1 range.");
30      }
31      block = block << 8 | charCode;
32    }
33    return output;
34  });
35
36  // decoder
37  // [https://gist.github.com/1020396] by [https://github.com/atk]
38  object.atob || (
39  object.atob = function (input) {
40    var str = String(input).replace(/=+$/, '');
41    if (str.length % 4 == 1) {
42      throw new InvalidCharacterError("'atob' failed: The string to be decoded is not correctly encoded.");
43    }
44    for (
45      // initialize result and counters
46      var bc = 0, bs, buffer, idx = 0, output = '';
47      // get next character
48      buffer = str.charAt(idx++);
49      // character found in table? initialize bit storage and add its ascii value;
50      ~buffer && (bs = bc % 4 ? bs * 64 + buffer : buffer,
51        // and if not first of each 4 characters,
52        // convert the first 8 bits to one ascii character
53        bc++ % 4) ? output += String.fromCharCode(255 & bs >> (-2 * bc & 6)) : 0
54    ) {
55      // try to find character in table (0-63, not found => -1)
56      buffer = chars.indexOf(buffer);
57    }
58    return output;
59  });
60
61}());