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JavaScript base64_decode function

A JavaScript equivalent of PHP’s base64_decode

url/base64_decode.js raw on github
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function base64_decode(data) {
  //  discuss at: http://phpjs.org/functions/base64_decode/
  // original by: Tyler Akins (http://rumkin.com)
  // improved by: Thunder.m
  // improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  // improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  //    input by: Aman Gupta
  //    input by: Brett Zamir (http://brett-zamir.me)
  // bugfixed by: Onno Marsman
  // bugfixed by: Pellentesque Malesuada
  // bugfixed by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  //   example 1: base64_decode('S2V2aW4gdmFuIFpvbm5ldmVsZA==');
  //   returns 1: 'Kevin van Zonneveld'
  //   example 2: base64_decode('YQ===');
  //   returns 2: 'a'

  var b64 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
  var o1, o2, o3, h1, h2, h3, h4, bits, i = 0,
    ac = 0,
    dec = '',
    tmp_arr = [];

  if (!data) {
    return data;
  }

  data += '';

  do { // unpack four hexets into three octets using index points in b64
    h1 = b64.indexOf(data.charAt(i++));
    h2 = b64.indexOf(data.charAt(i++));
    h3 = b64.indexOf(data.charAt(i++));
    h4 = b64.indexOf(data.charAt(i++));

    bits = h1 << 18 | h2 << 12 | h3 << 6 | h4;

    o1 = bits >> 16 & 0xff;
    o2 = bits >> 8 & 0xff;
    o3 = bits & 0xff;

    if (h3 == 64) {
      tmp_arr[ac++] = String.fromCharCode(o1);
    } else if (h4 == 64) {
      tmp_arr[ac++] = String.fromCharCode(o1, o2);
    } else {
      tmp_arr[ac++] = String.fromCharCode(o1, o2, o3);
    }
  } while (i < data.length);

  dec = tmp_arr.join('');

  return dec.replace(/\0+$/, '');
}

Please note that php.js uses JavaScript objects as substitutes for PHP arrays, they are the closest match to this hashtable-like data structure.

Please also note that php.js offers community built functions and goes by the McDonald’s Theory. We’ll put online functions that are far from perfect, in the hopes to spark better contributions. Do you have one? Then please just:

Other PHP functions in the url extension

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