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

prompt and alert can be done with native module, like in the prompt and alert example:

require 'native'
name = $$.prompt "Please enter your name"
$$.alert("Hello #{name}!")

This is intentional, to demonstrate another way to call JS since an example using native is already in the examples.

My idea was that... this syntax is slowly going to be deprecated. Already it drops a warning and asks to add a magic comment.

This may not work in future major versions of Opal (I mean, it will, but eg. String may need special conversion). Therefore I would suggest that this syntax is only presented to advanced users.

Created a new one using native:
https://gist.github.com/svoboda-jan/cc4d675bac8a966038c8aeb0a495b3ad

The motivation behind these scripts is to create an easy way to start learning ruby without having to install it.

So in the betting game a task may be:

• disallow betting to negative numbers
• warn the user and ask if he wants co continue the game with certain bank treshold

In the calendar it might be:

• to add support for leap years
• to highlight holidays

Another script I've created is to display Czech name days, using Base64 encoded data at the end of the file:
https://gist.github.com/svoboda-jan/25144fb6b734893dc4742ac52b54b869

Here the task could be to combine these scripts in some way, like displaying the name day in the calendar, think that wold be a good task to teach refactoring, because both scripts work with date.

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).