Docs test: add an average helper

README.md

@@ -1,3 +1,41 @@
 # test-scratch-repo
 
 Scratch repo for testing Pullfrog triggers.
+
+## API
+
+```js
+const { add, subtract, average, median } = require("./index");
+```
+
+### `add(a, b)`
+
+Returns the sum of `a` and `b`.
+
+```js
+add(1, 2); // 3
+```
+
+### `subtract(a, b)`
+
+Returns `a` minus `b`.
+
+```js
+subtract(5, 3); // 2
+```
+
+### `average(numbers)`
+
+Returns the arithmetic mean of an array of numbers. Returns `0` for an empty array and throws a `TypeError` if `numbers` is not an array of numbers.
+
+```js
+average([1, 2, 3, 4]); // 2.5
+```
+
+### `median(numbers)`
+
+Returns the middle value of an array of numbers, or the mean of the two middle values when the length is even. The input array is not mutated. Returns `0` for an empty array and throws a `TypeError` if `numbers` is not an array of numbers.
+
+```js
+median([4, 1, 3, 2]); // 2.5
+```

index.js

@@ -6,4 +6,23 @@ function subtract(a, b) {
   return a - b;
 }
 
-module.exports = { add, subtract };
+function average(numbers) {
+  if (!Array.isArray(numbers) || !numbers.every((n) => typeof n === "number")) {
+    throw new TypeError("average expects an array of numbers");
+  }
+  if (numbers.length === 0) return 0;
+  const total = numbers.reduce((sum, n) => sum + n, 0);
+  return total / numbers.length;
+}
+
+function median(numbers) {
+  if (!Array.isArray(numbers) || !numbers.every((n) => typeof n === "number")) {
+    throw new TypeError("median expects an array of numbers");
+  }
+  if (numbers.length === 0) return 0;
+  const sorted = [...numbers].sort((a, b) => a - b);
+  const mid = Math.floor(sorted.length / 2);
+  return sorted.length % 2 === 0 ? (sorted[mid - 1] + sorted[mid]) / 2 : sorted[mid];
+}
+
+module.exports = { add, subtract, average, median };

test.js

@@ -1,8 +1,31 @@
-const { add, subtract } = require("./index");
+const { add, subtract, average, median } = require("./index");
 
 const assert = require("assert");
 
 assert.strictEqual(add(1, 2), 3);
 assert.strictEqual(subtract(5, 3), 2);
+assert.strictEqual(average([1, 2, 3, 4]), 2.5);
+assert.strictEqual(average([]), 0);
+assert.throws(() => average(), TypeError);
+assert.throws(() => average(null), TypeError);
+assert.throws(() => average("123"), TypeError);
+assert.throws(() => average({ length: 2 }), TypeError);
+assert.throws(() => average([1, "2", 3]), TypeError);
+assert.throws(() => average([1, null]), TypeError);
+assert.strictEqual(median([3, 1, 2]), 2);
+assert.strictEqual(median([4, 1, 3, 2]), 2.5);
+assert.strictEqual(median([10, 9, 100]), 10);
+assert.strictEqual(median([]), 0);
+const unsorted = [3, 1, 2];
+median(unsorted);
+assert.deepStrictEqual(unsorted, [3, 1, 2]);
+assert.throws(() => median(), TypeError);
+assert.throws(() => median(null), TypeError);
+assert.throws(() => median("123"), TypeError);
+assert.throws(() => median({ length: 2 }), TypeError);
+assert.throws(() => median([1, "2", 3]), TypeError);
+assert.throws(() => median([1, null]), TypeError);
+
+assert.strictEqual(average([5]), 5);
 
 console.log("All tests passed!");