turns 9999999 into 9,999,999

beautify.js

// turns 9999999 into 9,999,999
function beautify(num) {
  var str = '';
  if (!isFinite(num)) return 'Infinity';
  if (num.toString().indexOf('e') != -1) return num.toString();
  num = Math.round(num * 10000000) / 10000000; // get rid of weird rounding errors
  num = Math.floor(num);
  num = (num + '').split('').reverse();
  for (var i in num) {
    if (i % 3 == 0 && i > 0) str = ',' + str;
    str = num[i] + str;
  }
  return str;
}