has anyone implemented autonumbering with iol technique?

This is a copy of a pastie by Dan. Can't find the original post:

function makePasswd() {
  var passwd = '';
  var chars = '0123456789';
  for (i = 1; i < 8; i++) {
    var c = Math.floor(Math.random() * chars.length + 1);
    passwd += chars.charAt(c)
  }
  return passwd;
}

//replace fid_21 with the field ID you want to enter the autonumber.
$("#_fid_21").val(makePasswd());