https://en.m.wikipedia.org/wiki/Jeffreys_prior

  a = {}
  for(let i = 0; i < 100000; i++){
    let n = Math.floor(Math.random() * 10);
    if( n in a )
      a[n] += 1
    else
      a[n] = 1
  }

{ '0': 9917, '1': 10015, '2': 9957, '3': 10107, '4': 10019, '5': 10037, '6': 10120, '7': 9914, '8': 10042, '9': 9872 }