craps simulator

README.md

craps toy/simulator

usage

➜  node craps-toy.js
┌─────────┬──────┬──────┬─────┬─────────────┐
│ (index) │ die1 │ die2 │ sum │   result    │
├─────────┼──────┼──────┼─────┼─────────────┤
│    0    │  1   │  4   │  5  │ 'point set' │
│    1    │  3   │  6   │  9  │  'neutral'  │
│    2    │  1   │  5   │  6  │  'neutral'  │
│    3    │  1   │  1   │  2  │  'neutral'  │
│    4    │  4   │  5   │  9  │  'neutral'  │
│    5    │  2   │  3   │  5  │ 'point win' │
│    6    │  3   │  5   │  8  │ 'point set' │
│    7    │  5   │  5   │ 10  │  'neutral'  │
│    8    │  2   │  4   │  6  │  'neutral'  │
│    9    │  2   │  6   │  8  │ 'point win' │
│   10    │  1   │  3   │  4  │ 'point set' │
│   11    │  2   │  4   │  6  │  'neutral'  │
│   12    │  2   │  5   │  7  │ 'seven out' │
└─────────┴──────┴──────┴─────┴─────────────┘
┌───────────────┬────────┐
│    (index)    │ Values │
├───────────────┼────────┤
│   rollCount   │   13   │
│   pointsSet   │   3    │
│   pointsWon   │   2    │
│  comeOutWins  │   0    │
│ comeOutLosses │   0    │
│   neutrals    │   7    │
└───────────────┴────────┘

craps-toy.js

'use strict';

function d6 () {
  return 1 + Math.floor(Math.random() * 6)
}

function tallyResults (history) {
  const resultsTemplate = {
    rollCount: 0,
    pointsSet: 0,
    pointsWon: 0,
    comeOutWins: 0,
    comeOutLosses: 0,
    neutrals: 0
  }

  return history.reduce((memo, roll) => {
    memo.rollCount++

    switch (roll.result) {
      case 'neutral':
        memo.neutrals++;
        break;
      case 'point set':
        memo.pointsSet++;
        break;
      case 'point win':
        memo.pointsWon++;
        break;
      case 'comeout win':
        memo.comeOutWins++;
        break;
      case 'comeout loss':
        memo.comeOutLosses++;
        break;
    }

    return memo
  }, resultsTemplate)
}

let history = []

let isComeOut = true
let point
while(true) {
  const dice = [d6(), d6()].sort()

  let roll = {
    die1: dice[0],
    die2: dice[1],
    sum: dice.reduce((m, r) => { return m + r }, 0)
  }

  // game logic based on: https://github.com/tphummel/dice-collector/blob/master/PyTom/Dice/logic.py
  
  if (isComeOut) {
    if ([2,3,12].indexOf(roll.sum) !== -1) {
      roll.result = 'comeout loss'
    } else if ([7,11].indexOf(roll.sum) !== -1 ) {
      roll.result = 'comeout win'
    } else {
      point = roll.sum
      roll.result = 'point set'
      isComeOut = false
    }
  } else {
    if (roll.sum === point) {
      roll.result = 'point win'
      isComeOut = true
    } else if (roll.sum === 7) {
      roll.result = 'seven out'
    } else {
      roll.result = 'neutral'
    }
  }

  history.push(roll)

  if (roll.result === 'seven out') break
}
console.table(history)
console.table(tallyResults(history))