I'm using this handy Javascript function to decode a base64 string and get an array in return.

This is the string:

base64_decode_array('6gAAAOsAAADsAAAACAEAAAkBAAAKAQAAJgEAACcBAAAoAQAA')

This is what's returned:

234,0,0,0,235,0,0,0,236,0,0,0,8,1,0,0,9,1,0,0,10,1,0,0,38,1,0,0,39,1,0,0,40,1,0,0

The problem is I don't really understand the javascript function:

var base64chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'.split("");
var base64inv = {}; 
for (var i = 0; i < base64chars.length; i++) { 
  base64inv[base64chars[i]] = i; 
}
function base64_decode_array (s)
{
  // remove/ignore any characters not in the base64 characters list
  //  or the pad character -- particularly newlines
  s = s.replace(new RegExp('[^'+base64chars.join("")+'=]', 'g'), "");

  // replace any incoming padding with a zero pad (the 'A' character is zero)
  var p = (s.charAt(s.length-1) == '=' ? 
          (s.charAt(s.length-2) == '=' ? 'AA' : 'A') : ""); 

  var r = [];

  s = s.substr(0, s.length - p.length) + p;

  // increment over the length of this encrypted string, four characters at a time
  for (var c = 0; c < s.length; c += 4) {

    // each of these four characters represents a 6-bit index in the base64 characters list
    //  which, when concatenated, will give the 24-bit number for the original 3 characters
    var n = (base64inv[s.charAt(c)] << 18) + (base64inv[s.charAt(c+1)] << 12) +
            (base64inv[s.charAt(c+2)] << 6) + base64inv[s.charAt(c+3)];


    // split the 24-bit number into the original three 8-bit (ASCII) characters
    r.push((n >>> 16) & 255);
    r.push((n >>> 8) & 255);
    r.push(n & 255);


  }
   // remove any zero pad that was added to make this a multiple of 24 bits
  return r;
}

What's the function of those "<<<" and ">>>" characters. Or is there a function like this for Python?