London | ITP-JAN-2026 | Said Fayaz Sadat | Sprint 1 | coursework/sprint 1

Sprint-1/fix/median.js

@@ -6,9 +6,29 @@
 // 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;
+  // If list is not an array, return null
+  if (!Array.isArray(list)) return null;
+
+  // Filter only real numbers
+  const numbers = list.filter((item) => Number.isFinite(item));
+
+  // If no numbers, return null
+  if (numbers.length === 0) return null;
+
+
+  // Sort numerically
+  numbers.sort((a, b) => a - b);
+
+  const mid = Math.floor(numbers.length / 2);
+
+  // Odd length → return middle
+  if (numbers.length % 2 === 1) {
+    return numbers[mid];
+  }
+
+  // Even length → average of two middle values
+  return (numbers[mid - 1] + numbers[mid]) / 2;
 }
 
+
 module.exports = calculateMedian;

Sprint-1/implement/dedupe.js

@@ -1 +1,14 @@
-function dedupe() {}
+function dedupe(arr) {
+  if (!Array.isArray(arr)) return null; 
+
+  const seen = [];
+
+  for (const item of arr) {
+    if (!seen.includes(item)) {
+      seen.push(item);
+    }
+  }
+
+  return seen;
+}
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -13,15 +13,31 @@ E.g. dedupe([1, 2, 1]) target output: [1, 2]
 
 // Acceptance Criteria:
 
-// 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");
-
-// Given an array with no duplicates
-// When passed to the dedupe function
-// Then it should return a copy of the original array
-
-// Given an array with strings or numbers
-// When passed to the dedupe function
-// Then it should remove the duplicate values, preserving the first occurence of each element
+describe("dedupe", () => {
+  // Given an empty array
+  // When passed to the dedupe function
+  // Then it should return an empty array
+  test("given an empty array, it returns an empty array", () => {
+    expect(dedupe([])).toEqual([]);
+  });
+
+  // Given an array with no duplicates
+  // When passed to the dedupe function
+  // Then it should return a copy of the original array
+  test("returns a copy when no duplicates exist", () => {
+    const input = [1, 2, 3];
+    const output = dedupe(input);
+
+    expect(output).toEqual([1, 2, 3]);
+    expect(output).not.toBe(input); // ensures it's a new array, not the same reference
+  });
+
+  // Given an array with strings or numbers
+  // When passed to the dedupe function
+  // Then it should remove the duplicate values, preserving the first occurrence
+  test("removes duplicates and preserves first occurrence", () => {
+    expect(dedupe(['a','a','a','b','b','c'])).toEqual(['a','b','c']);
+    expect(dedupe([5, 1, 1, 2, 3, 2, 5, 8])).toEqual([5, 1, 2, 3, 8]);
+    expect(dedupe([1, 2, 1])).toEqual([1, 2]);
+  });
+});

Sprint-1/implement/max.js

@@ -1,4 +1,24 @@
 function findMax(elements) {
+  if (!Array.isArray(elements)) {
+    return null;
+  }
+
+  // If the array is truly empty, return -Infinity
+  if (elements.length === 0) {
+    return -Infinity;
+  }
+
+  // Filter only numeric values
+  const numbers = elements.filter((item) => Number.isFinite(item));
+
+  // If there are no numeric values but the array wasn't empty, return null
+  if (numbers.length === 0) {
+    return null;
+  }
+
+  // Otherwise, return the largest number
+  return Math.max(...numbers);
 }
 
 module.exports = findMax;
+

Sprint-1/implement/max.test.js

@@ -16,28 +16,49 @@ 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("given an empty array, returns -Infinity", () => {
+  expect(findMax([])).toBe(-Infinity);
+});
+
 
 // Given an array with one number
 // When passed to the max function
 // Then it should return that number
+test("given an array with one number, returns that number", () => {
+  expect(findMax([5])).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("given an array with both positive and negative numbers, returns the largest", () => {
+  expect(findMax([30, 50, 10, 40])).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("given an array with just negative numbers, returns the closest to zero", () => {
+  expect(findMax([-10, -5, -20])).toBe(-5);
+});
 
 // Given an array with decimal numbers
 // When passed to the max function
 // Then it should return the largest decimal number
+test("given an array with decimal numbers, returns the largest", () => {
+  expect(findMax([3.14, 2.71, 1.41])).toBe(3.14);
+});
 
 // 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("given an array with non-number values, returns the largest number", () => {
+  expect(findMax(['hey', 10, 'hi', 60, 10])).toBe(60);
+});
 
 // 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("given an array with only non-number values, returns the least surprising value", () => {
+  expect(findMax(['hey', 'hi', 'hello'])).toBe(null);
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,20 @@
 function sum(elements) {
+  if (!Array.isArray(elements)) {
+    return 0;
+  }
+
+  // Filter only numeric values
+  const numbers = elements.filter((item) => Number.isFinite(item));
+
+  // If no numeric values, return 0
+  if (numbers.length === 0) {
+    return 0;
+  }
+
+  // Add the numbers
+  return numbers.reduce(function (total, value) {
+    return total + value;
+  }, 0);
 }
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -13,24 +13,41 @@ 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", () => {
+  expect(sum([])).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 just one number, returns that number", () => {
+  expect(sum([5])).toBe(5);
+});
 
 // 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 containing negative numbers, returns the correct total sum", () => {
+  expect(sum([-10, 20, -5])).toBe(5);
+});
 
 // 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 decimal/float numbers, returns the correct total sum", () => {
+  expect(sum([3.14, 2.71, 1.41])).toBe(7.26);
+});
 
 // 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 containing non-number values, ignores non-numerical values and returns the sum of numerical elements", () => {
+  expect(sum(['hey', 10, 'hi', 60, 10])).toBe(80);
+});
 
 // 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 only non-number values, returns the least surprising value", () => {
+  expect(sum(['hey', 'hi', 'hello'])).toBe(0);
+});

Sprint-1/refactor/includes.js

@@ -1,6 +1,6 @@
 // Refactor the implementation of includes to use a for...of loop
 
-function includes(list, target) {
+/* function includes(list, target) {
   for (let index = 0; index < list.length; index++) {
     const element = list[index];
     if (element === target) {
@@ -9,5 +9,16 @@ function includes(list, target) {
   }
   return false;
 }
+  */
 
-module.exports = includes;
+
+
+function includes(list, target){
+  for ( let element of list){
+    if (element === target){
+      return true;
+    }
+  }
+  return false;
+}
+module.exports = includes;