probability_calculator.js

const Random = require("random-js").Random;

function deckProbabilityTest(cycles = 1) {
  let random = new Random();
  let results = []

  let originalDeck = [1,2,3,4,5,6]
  let totalCards = originalDeck.length
  let desiredCardAtEnd = 5

  let firstCardIndex
  let secondCardIndex
  let thirdCardIndex
  
  let deckAfterFirstDraw
  let deckAfterSecondDraw

  for (let x = 0; x < cycles; x++) {

    // Compra da Primeira Carta
    firstCardIndex = random.integer(0, totalCards - 1)
    deckAfterFirstDraw = originalDeck.filter(n => n != firstCardIndex)
    
    // Drawing the Second card.
    secondCardIndex = random.integer(0, deckAfterFirstDraw.length - 1)
    deckAfterSecondDraw = deckAfterFirstDraw.filter(n => n != secondCardIndex)

    // Drawing the Third card.
    thirdCardIndex = random.integer(0, deckAfterSecondDraw.length - 1)

    // Here we just push the final selected card to an Array.
    results.push(deckAfterSecondDraw[thirdCardIndex])
  }

  // Retorna a divisão dos resultados bem sucedidos com o número total de testes.
  return results.filter(r => r == desiredCardAtEnd).length / cycles
}