implement correct median calculation

Author: Pretty Taruvinga

Sprint-1/fix/median.js

@@ -6,9 +6,21 @@
 // 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;
+  // Filter out non-numeric values and sort the remaining numbers
+  const numbers = list
+    .filter((x) => typeof x === "number" && !isNaN(x))
+    .sort((a, b) => a - b);
+
+  if (numbers.length === 0) {
+    return null;
+  }
+
+  const mid = Math.floor(numbers.length / 2);
+  if (numbers.length % 2 === 0) {
+    return (numbers[mid - 1] + numbers[mid]) / 2;
+  } else {
+    return numbers[mid];
+  }
 }
 
 module.exports = calculateMedian;