CountTo21

Background

Blackjack is one of the few casino games with ‘memory’ in that the previous games change the possible outcome of future games. As a result, it is possible to keep track of previously played cards and see how the advantage can shift from the House to the player with changes in strategy.

Functionality

• Players of Counting to 21 will be able to:
• Play a hand of Blackjack
• Make bets up to the limit of the bankroll
• See the probability of getting dealt different point levels and have it change with the card count in real time
• Let an AI make game and betting decisions until the end of the decks In addition, the project will include:
• An About modal describing the rules of the game and another explaining the probability calculations

Architecture and Technologies

This project will be implemented with the following technologies:

• Vanilla JavaScript for the game logic and Math.js for the calculation of the probabilities.
• charts.js for the visualization
• Webpack to bundle and serve up the various scripts In addition to the webpack file, there will be three scripts involved in this project:
• blackjack.js: contains the game logic and the css manipulation logic.
• probability.js: creates the probability tree, keeps track of the card count, and calculates the expected value for the AI logic.
• chart.js: handles the chart rendering logic.
• player_ai.js: calculates the probability of winning for each hand and then makes betting recommendations based on them.

Code Example

Probability Function

p(num){

  let values = [];
  let cardKeys = [];
  for (var i = 0; i < blackjackValues.length; i++) {
    for (var j = i; j < blackjackValues.length; j++) {
      if (blackjackValues[i] + blackjackValues[j] === num) {
        values.push([blackjackValues[i], blackjackValues[j]]);
        cardKeys.push([valueStrings[i], valueStrings[j]]);
      }
    }
  }

  let numerator = 0;
  cardKeys.forEach(pair => {
    if(pair[0] === pair[1]){
      if (this.cardCount[pair[0]] > 1) {
        numerator += (math.combinations(this.cardCount[pair[0]], 2));
      }
    } else {
      if (this.cardCount[pair[0]] >= 1 && this.cardCount[pair[1]] >= 1) {
        numerator += ((math.combinations(this.cardCount[pair[0]], 1) * math.combinations(this.cardCount[pair[1]], 1)));
      }
    }
  });
  return (numerator / math.combinations(this.deckCount, 2));
}