Glasgow| 2026-ITP-Jan | Tuan Nguyen| Sprint 1 | Array-and-Loop.

Sprint-1/fix/median.js

@@ -6,9 +6,26 @@
 // 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;
+  // validation
+  if (!Array.isArray(list)) return null;
+  if (list.length === 0) return null;
+
+  // sorted copy for correct median calculation
+  const sorted = [...list]
+    .filter((items) => typeof items === "number" && !isNaN(items))
+    .sort((a, b) => a - b);
+
+  if (sorted.length === 0) return null;
+
+  let correctMedian;
+  if (sorted.length % 2 === 0) {
+    const mid = sorted.length / 2;
+    correctMedian = (sorted[mid - 1] + sorted[mid]) / 2;
+  } else {
+    const mid = Math.floor(sorted.length / 2);
+    correctMedian = sorted[mid];
+  }
+  return correctMedian;
 }
 
 module.exports = calculateMedian;

Sprint-1/implement/dedupe.js

@@ -1 +1,12 @@
-function dedupe() {}
+function dedupe(inputArray) {
+  if (inputArray.length === 0) return inputArray;
+  let fixArray = [];
+  for (const item of inputArray) {
+    if (!fixArray.includes(item)) {
+      fixArray.push(item);
+    }
+  }
+  return fixArray;
+}
+
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -1,4 +1,5 @@
 const dedupe = require("./dedupe.js");
+const findMax = require("./max.js");
 /*
 Dedupe Array
 
@@ -16,13 +17,36 @@ E.g. dedupe([1, 2, 1]) returns [1, 2]
 // Given an empty array
 // When passed to the dedupe function
 // Then it should return an empty array
-test.todo("given an empty array, it returns an empty array");
+test("with input of empty array should return, empty array", () => {
+  let emptyArray = [];
+  expect(dedupe(emptyArray)).toEqual([]);
+});
 
 // Given an array with no duplicates
 // When passed to the dedupe function
 // Then it should return a copy of the original array
+test("with input of array with no duplicates should return a copy of original array", () => {
+  const normalArray = [1, 2, 3, 4, 5, 6, 10];
+  const expected = [1, 2, 3, 4, 5, 6, 10]; // separate copy
+
+  const result = dedupe(normalArray);
+
+  // 1. Correct values
+  expect(result).toEqual(expected);
+
+  // 2. Different array in memory
+  expect(result).not.toBe(normalArray);
+
+  // 3. Original array not mutated
+  expect(normalArray).toEqual(expected);
+}
+);
 
 // Given an array of strings or numbers
 // When passed to the dedupe function
-// Then it should return a new array with duplicates removed while preserving the 
+// Then it should return a new array with duplicates removed while preserving the
 // first occurrence of each element from the original array.
+test("with input of empty array should return, empty array", () => {
+  let mixValueArray = [1, 1, 1, 2, 2, "Hello", "Hello", "Hello", 3, 4, 4, 5];
+  expect(dedupe(mixValueArray)).toEqual([1, 2, "Hello", 3, 4, 5]);
+});

Sprint-1/implement/max.js

@@ -1,4 +1,13 @@
 function findMax(elements) {
+  if (elements.length === 0) return -Infinity;
+
+  const filteredArray = elements.filter(
+    (item) => typeof item === "number" && !isNaN(item)
+  );
+  if (filteredArray.length === 0) return null;
+  const sortedArray = filteredArray.sort((a, b) => a - b);
+  const maxArrayValue = sortedArray[sortedArray.length - 1];
+  return maxArrayValue;
 }
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -16,28 +16,55 @@ const findMax = require("./max.js");
 // When passed to the max function
 // Then it should return -Infinity
 // Delete this test.todo and replace it with a test.
-test.todo("given an empty array, returns -Infinity");
+test("when an empty array push into the function it should return empty array", () => {
+  let emptyArray = [];
+  expect(findMax(emptyArray)).toEqual(-Infinity);
+});
 
 // Given an array with one number
 // When passed to the max function
 // Then it should return that number
+test("When an array have only one number value", () => {
+  let mixArray = ["Hello", "Hi", null, undefined, 5];
+  expect(findMax(mixArray)).toBe(5);
+});
 
 // Given an array with both positive and negative numbers
 // When passed to the max function
 // Then it should return the largest number overall
+test("When an array have only one number value", () => {
+  let mixArray = [-5, 3, 10, -11, -12, -20, 50];
+  expect(findMax(mixArray)).toBe(50);
+});
 
 // Given an array with just negative numbers
 // When passed to the max function
 // Then it should return the closest one to zero
+test("When an array have only one number value", () => {
+  let mixArray = [-1, -4, -5, -6 - 2, -3, -10];
+  expect(findMax(mixArray)).toBe(-1);
+});
 
 // Given an array with decimal numbers
 // When passed to the max function
 // Then it should return the largest decimal number
+test("When an array have decimal number value", () => {
+  let decimalArray = [2.3, 1.5, 6.5, 10.2, 11.5];
+  expect(findMax(decimalArray)).toBe(11.5);
+});
 
 // Given an array with non-number values
 // When passed to the max function
 // Then it should return the max and ignore non-numeric values
+test("When an array have number value mix with non-number value, the return should only be number value", () => {
+  let decimalArray = ["Hello", "Hi", 1, 12312321n, undefined];
+  expect(findMax(decimalArray)).toBe(1);
+});
 
 // Given an array with only non-number values
 // When passed to the max function
 // Then it should return the least surprising value given how it behaves for all other inputs
+test("When an array have only non-number values ", () => {
+  let nonNumberArray = ["Hello", "Hi", undefined, null, "23"];
+  expect(findMax(nonNumberArray)).toBe(null);
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,14 @@
 function sum(elements) {
+  if (elements.length === 0) return 0;
+  let filteredArray = elements.filter(
+    (items) => typeof items === "number" && !isNaN(items)
+  );
+  if (filteredArray.length === 0) return null;
+  let sumTotal = 0;
+  for (let i = 0; i < filteredArray.length; i++) {
+    sumTotal += filteredArray[i];
+  }
+  return sumTotal;
 }
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -13,24 +13,47 @@ const sum = require("./sum.js");
 // Given an empty array
 // When passed to the sum function
 // Then it should return 0
-test.todo("given an empty array, returns 0")
+test("given an empty array, returns 0", () => {
+  let emptyArray = [];
+  expect(sum(emptyArray)).toBe(0);
+});
 
 // Given an array with just one number
 // When passed to the sum function
 // Then it should return that number
+test("given an array with 1 number value, returns that number value", () => {
+  let mixArray = ["1", "Hello", 20, null, undefined];
+  expect(sum(mixArray)).toBe(20);
+});
 
 // Given an array containing negative numbers
 // When passed to the sum function
 // Then it should still return the correct total sum
+test("given an array with 1 number value, returns that number value", () => {
+  let negativeArray = [-1, -20, -30, -50, -60];
+  expect(sum(negativeArray)).toBe(-161);
+});
 
 // Given an array with decimal/float numbers
 // When passed to the sum function
 // Then it should return the correct total sum
+test("given an array with 1 number value, returns that number value", () => {
+  let negativeArray = [1.5, 20.3, 50.43, 6.7, 10.5];
+  expect(sum(negativeArray)).toBeCloseTo(89.43,2);
+});
 
 // Given an array containing non-number values
 // When passed to the sum function
 // Then it should ignore the non-numerical values and return the sum of the numerical elements
+test("given an array with 1 number value, returns that number value", () => {
+  let mixedArray2 = ["Hello", 20.17, null, 9.7, undefined];
+  expect(sum(mixedArray2)).toBe(29.87);
+});
 
 // Given an array with only non-number values
 // When passed to the sum function
 // Then it should return the least surprising value given how it behaves for all other inputs
+test("given an array with 1 number value, returns that number value", () => {
+  let nonNumberArray = ["Hello", "2", null, "@", undefined];
+  expect(sum(nonNumberArray)).toBe(null);
+});