3-get-card-value.js

// This problem involves playing cards: https://en.wikipedia.org/wiki/Standard_52-card_deck

// You will need to implement a function getCardValue
// the function takes a single parameter, a string representing a playing card
// the function should return the numerical value of the card
// the first test and first case is written for you
// complete the rest of the tests and cases
// write one test at a time, and make it pass, build your solution up methodically
// just make one change at a time -- don't rush -- programmers are deep and careful thinkers
function getCardValue(card) {
  const rank = card.slice(0, -1).toUpperCase(); // Extract rank by removing suit

  // Handle Ace
  if (rank === "A") {
    return 11;
  }

  // Handle Face Cards and 10
  const faceRanks = ["K", "Q", "J", "10"];
  if (faceRanks.includes(rank)) {
    return 10;
  }

  // Handle Number Cards (2–9) with strict validation
  const numberRanks = ["2", "3", "4", "5", "6", "7", "8", "9"];
  if (numberRanks.includes(rank)) {
    return parseInt(rank, 10);
  }

  // Handle invalid ranks
  throw new Error(`Invalid or unrecognized card rank: "${rank}"`);
}

// The line below allows us to load the getCardValue function into tests in other files.
// This will be useful in the "rewrite tests with jest" step.
module.exports = getCardValue;

// You need to write assertions for your function to check it works in different cases
// we're going to use this helper function to make our assertions easier to read
// if the actual output matches the target output, the test will pass
function assertEquals(actualOutput, targetOutput) {
  console.assert(
    actualOutput === targetOutput,
    `Expected ${actualOutput} to equal ${targetOutput}`
  );
}
// Acceptance criteria:

// Given a card string in the format "A♠" (representing a card in blackjack - the last character will always be an emoji for a suit, and all characters before will be a number 2-10, or one letter of J, Q, K, A),
// When the function getCardValue is called with this card string as input,
// Then it should return the numerical card value
const aceofSpades = getCardValue("A♠");
assertEquals(aceofSpades, 11);

// Handle Number Cards (2-10):
// Given a card with a rank between "2" and "9",
// When the function is called with such a card,
// Then it should return the numeric value corresponding to the rank (e.g., "5" should return 5).
const fiveofHearts = getCardValue("5♥");
assertEquals(fiveofHearts, 5);
// ====> write your test here, and then add a line to pass the test in the function above

// Handle Face Cards (J, Q, K):
// Given a card with a rank of "10," "J," "Q," or "K",
// When the function is called with such a card,
// Then it should return the value 10, as these cards are worth 10 points each in blackjack.

// Handle Ace (A):
// Given a card with a rank of "A",
// When the function is called with an Ace,
// Then it should, by default, assume the Ace is worth 11 points, which is a common rule in blackjack.

// Handle Invalid Cards:
// Given a card with an invalid rank (neither a number nor a recognized face card),
// When the function is called with such a card,
// Then it should throw an error indicating "Invalid card rank."
//Stretch (personal)
// Handle Face Cards (J, Q, K):
const kingOfClubs = getCardValue("K♣");
assertEquals(kingOfClubs, 10);

const queenOfDiamonds = getCardValue("Q♦");
assertEquals(queenOfDiamonds, 10);

const jackOfSpades = getCardValue("J♠");
assertEquals(jackOfSpades, 10);

const tenOfHearts = getCardValue("10♥");
assertEquals(tenOfHearts, 10);
// Handle Invalid Cards:
try {
  getCardValue("Z♠");
  console.assert(false, "Expected an error for invalid card rank");
} catch (error) {
  console.assert(
    error.message === 'Invalid or unrecognized card rank: "Z"',
    `Expected error message 'Invalid or unrecognized card rank: "Z"', got "${error.message}"`
  );
}