Function for pretty-printing integers, placing spaces every third digit from the end.

gistfile1.js

var _f = function(i){
  var s = new String(i);
  var r = '';
  for(c = s.length-1; c >= 0; c--){
    r = s[c] + r
    if(c !== 0 && (s.length-c) % 3 === 0) r = ' ' + r
  }
  return r;
}