implement getCardValue with JSDoc and console.assert tests for all card types

Author: remimarcelle

Sprint-3/1-implement-and-rewrite-tests/implement/3-get-card-value.js

@@ -21,8 +21,49 @@
 // After you have implemented the function, write tests to cover all the cases, and
 // execute the code to ensure all tests pass.
 
+/**
+ * Returns the numerical value of a playing card.
+ *
+ * A standard deck has 4 suits: ♠ (spades), ♥ (hearts), ♦ (diamonds), ♣ (clubs)
+ * Each card is written as a rank followed by a suit symbol e.g. "A♠", "10♥", "K♦"
+ *
+ * @param {string} card - A string representing a playing card e.g. "A♠", "10♥", "K♦", "7♣"
+ * @returns {number} - The numerical value of the card:
+ *   - Ace ("A") returns 11
+ *   - Face cards ("J", "Q", "K") return 10
+ *   - Number cards ("2" to "10") return their numeric value
+ * @throws {Error} - If the card string is not in a valid format e.g. "invalid" or "1♠"
+ *
+ * @example
+ * getCardValue("A♠") // returns 11
+ * getCardValue("10♥") // returns 10
+ * getCardValue("K♦") // returns 10
+ * getCardValue("7♣") // returns 7
+ */
 function getCardValue(card) {
   // TODO: Implement this function
+  // NEW: The suit symbol (♠ ♥ ♦ ♣) always takes up 2 characters in JavaScript
+  // slice(0, -2) means "give me everything except the last 2 characters"
+  // so "A♠" becomes "A", "10♥" becomes "10", "K♦" becomes "K"
+  // MDN: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/slice
+  const rank = card.slice(0, -1);
+
+  // ✨ NEW: Ace is always worth 11
+  if (rank === "A") return 11;
+
+  // ✨ NEW: Face cards - Jack, Queen and King are all worth 10
+  if (rank === "J" || rank === "Q" || rank === "K") return 10;
+
+  // ✨ NEW: Number() converts a string like "9" into the actual number 9
+  // so we can check if it falls in the valid range of 2 to 10
+  // MDN: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number
+  const numValue = Number(rank);
+  if (numValue >= 2 && numValue <= 10) return numValue;
+
+  // ✨ NEW: If we reach this line, none of the above matched
+  // throw stops the function and sends an error back to whoever called it
+  // MDN: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/throw
+  throw new Error(`Invalid card: ${card}`);
 }
 
 // The line below allows us to load the getCardValue function into tests in other files.
@@ -38,17 +79,52 @@ function assertEquals(actualOutput, targetOutput) {
 }
 
 // TODO: Write tests to cover all outcomes, including throwing errors for invalid cards.
-// Examples:
-assertEquals(getCardValue("9♠"), 9);
+
+// Ace cards - always 11 regardless of suit
+assertEquals(getCardValue("A♠"), 11);
+assertEquals(getCardValue("A♥"), 11);
+
+// Number cards - return their face value as a number
+assertEquals(getCardValue("2♦"), 2); // boundary: lowest number card
+assertEquals(getCardValue("9♣"), 9);
+assertEquals(getCardValue("10♥"), 10); // boundary: highest number card
+
+// Face cards - Jack, Queen and King all return 10
+assertEquals(getCardValue("J♣"), 10);
+assertEquals(getCardValue("Q♦"), 10);
+assertEquals(getCardValue("K♠"), 10);
 
 // Handling invalid cards
+// try/catch lets us test that an error IS thrown
+// try: runs the code. catch: catches the error if one is thrown
+// MDN: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/try...catch
 try {
   getCardValue("invalid");
-
   // This line will not be reached if an error is thrown as expected
-  console.error("Error was not thrown for invalid card 😢");
+  console.error("Error was not thrown for invalid card ");
 } catch (e) {
-  console.log("Error thrown for invalid card 🎉");
+  console.log("Error thrown for invalid card ");
 }
 
 // What other invalid card cases can you think of?
+
+try {
+  getCardValue("1♠"); // 1 is not a valid rank - valid ranks are 2 through A
+  console.error("Error was not thrown for rank 1 ");
+} catch (e) {
+  console.log("Error thrown for rank 1 ");
+}
+
+try {
+  getCardValue("11♥"); // 11 is not a valid rank - valid ranks are 2 through A
+  console.error("Error was not thrown for rank 11 ");
+} catch (e) {
+  console.log("Error thrown for rank 11 ");
+}
+
+try {
+  getCardValue("A"); // missing suit
+  console.error("Error was not thrown for missing suit ");
+} catch (e) {
+  console.log("Error thrown for missing suit ");
+}