A dice betting game using Opal Ruby to Javascript source-to-source compiler

dice_betting_game.rb

# Dice Betting Game, https://opalrb.com/try/
bank = 100;
while bank > 0 do
  bet = `prompt("Place your bet")`.to_i
  dice1 = (rand * 6).ceil
  dice2 = (rand * 6).ceil
  outcome = dice1 == dice2
  bank += bet if outcome
  bank -= bet unless outcome
  puts "Numbers are: #{dice1} #{dice2}"
  puts outcome_txt = outcome ? "You Win" : "You Lose"
  outcome_txt += ", bank is now #{bank}"

  puts "Bank is now #{bank}"
  `alert(outcome_txt)`
end

Is there a standalone example? E. g. can I just put the ruby code into a .html file too, or do
I need to use "opal --compile"?

Would be nice to add it to the official examples, if it works. Right now I am not sure how to
get it to work (I am an opal-noob at this point in time).