Merge branch 'coursework/sprint-1-fix' into coursework/sprint-1-data-groups

Author: Richiealx

Sprint-1/fix/median.js

@@ -6,9 +6,33 @@
 // or 'list' has mixed values (the function is expected to sort only numbers).
 
 function calculateMedian(list) {
-  const middleIndex = Math.floor(list.length / 2);
-  const median = list.splice(middleIndex, 1)[0];
-  return median;
+  // Return null immediately if the input is not an array
+  if (!Array.isArray(list)) {
+    return null;
+  }
+
+  // Keep only real numeric values
+  const numbersOnly = list.filter(
+    (item) => typeof item === "number" && !Number.isNaN(item)
+  );
+
+  // Return null if the array contains no numbers
+  if (numbersOnly.length === 0) {
+    return null;
+  }
+
+  // Create a sorted copy so the original input is not changed
+  const sortedNumbers = [...numbersOnly].sort((a, b) => a - b);
+
+  const middleIndex = Math.floor(sortedNumbers.length / 2);
+
+  // For an even-length array, median is the average of the two middle values
+  if (sortedNumbers.length % 2 === 0) {
+    return (sortedNumbers[middleIndex - 1] + sortedNumbers[middleIndex]) / 2;
+  }
+
+  // For an odd-length array, median is the middle value
+  return sortedNumbers[middleIndex];
 }
 
 module.exports = calculateMedian;