London | May-2025 | Halyna Kozlovska | Module Data Groups | Sprint 1

Sprint-1/fix/median.js

@@ -6,9 +6,17 @@
 // 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 (!Array.isArray(list)) return null;
+
+  const numbersList = list.filter(Number.isFinite).sort((a, b) => a - b);
+
+  const listLength = numbersList.length;
+  if (listLength === 0) return null;
+
+  const middleIndex = Math.floor(listLength / 2);
+  return listLength % 2 !== 0
+    ? numbersList[middleIndex]
+    : (numbersList[middleIndex - 1] + numbersList[middleIndex]) / 2;
 }
 
 module.exports = calculateMedian;

Sprint-1/implement/dedupe.js

@@ -1 +1,10 @@
-function dedupe() {}
+function dedupe(array) {
+  let result = [];
+
+  for (const item of array) {
+    if (!result.includes(item)) result.push(item);
+  }
+
+  return result;
+}
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -16,12 +16,22 @@ E.g. dedupe([1, 2, 1]) target output: [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");
+describe("dedupeArray", () => {
+  test("given an empty array, return 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("given an array with no duplicates, return a copy of the original array", () => {
+    expect(dedupe([1,2,3,4,5])).toEqual([1,2,3,4,5]);
+  });
 
 // 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
+  test("given an array with strings or numbers, remove the duplicate values, preserving the first occurence of each element", () => {
+    expect(dedupe([1, "test", 3, "test", 1])).toEqual([1, "test", 3]);
+  });
+})

Sprint-1/implement/max.js

@@ -1,4 +1,12 @@
 function findMax(elements) {
+  let maxElement = -Infinity;
+
+  for (const element of elements) {
+    if (typeof element === "number" && !isNaN(element)) {
+      if (element > maxElement) maxElement = element;
+    }
+  }
+  return maxElement;
 }
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -16,28 +16,51 @@ 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.todo("given an empty array, returns -Infinity");
+describe("findMax", () => {
+  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, return that number", () => {
+    expect(findMax([3])).toBe(3)
+  });
 
 // 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, return the largest number overall", () => {
+    expect(findMax([-5,47,100,-35])).toBe(100);
+  });
 
 // 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, return the closest one to zero", () => {
+    expect(findMax([-3,-7,-25,-77,-8])).toBe(-3);
+  });
 
 // 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, return the largest decimal number", () => {
+    expect(findMax([3.5, 8.6, 2.75, 75.25, 1.05])).toBe(75.25);
+  });
 
 // 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, return the max and ignore non-numeric values", () => {
+    expect(findMax(["test", "hello world", 45, "undefined", 90, 4])).toBe(90);
+  });
 
 // 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, return the least surprising value given how it behaves for all other inputs", () => {
+    expect(findMax(["test", null, undefined, true])).toBe(-Infinity);
+  });
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,12 @@
 function sum(elements) {
+  let sum = 0;
+
+  for (const element of elements) {
+    if (typeof element === "number" && !isNaN(element)) {
+      sum += element;
+    }
+  }
+  return Math.round(sum * 100) / 100;;
 }
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -13,24 +13,43 @@ 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")
+describe("sumElements", () => {
+  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
+  // Then it should return that number
+  test("given an array with just one number, return that number", () => {
+    expect(sum([7])).toBe(7);
+  });
 
 // Given an array containing negative numbers
 // When passed to the sum function
-// Then it should still return the correct total sum
+  // Then it should still return the correct total sum
+  test("given an array containing negative numbers, return the correct total sum", () => {
+    expect(sum([-5, -15, -4, -25])).toBe(-49);
+  });
 
 // Given an array with decimal/float numbers
 // When passed to the sum function
-// Then it should return the correct total sum
+  // Then it should return the correct total sum
+  test("given an array with decimal/float numbers, return the correct total sum", () => {
+    expect(sum([2.5, 15.75, 20.15, 1.55])).toBeCloseTo(39.95, 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 containing non-number values, ignore the non-numerical values and return the sum of the numerical elements", () => {
+     expect(sum(["text", 17, "undefined", 23])).toBe(40);
+   });
 
 // 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, return the least surprising value given how it behaves for all other inputs", () => {
+    expect(sum(["test", null, undefined, true, "25"])).toBe(0);
+  });
+})

Sprint-1/refactor/includes.js

@@ -1,11 +1,8 @@
 // Refactor the implementation of includes to use a for...of loop
 
 function includes(list, target) {
-  for (let index = 0; index < list.length; index++) {
-    const element = list[index];
-    if (element === target) {
-      return true;
-    }
+  for (const item of list) {
+    if (item === target) return true;
   }
   return false;
 }

Sprint-1/refactor/includes.test.js

@@ -6,33 +6,33 @@ test("returns true when target is in array", () => {
   const currentOutput = includes(["a", "b", "c", "d"], "c");
   const targetOutput = true;
 
-  expect(currentOutput).toEqual(targetOutput);
+  expect(currentOutput).toBe(targetOutput);
 });
 
 test("returns false when target not in array", () => {
   const currentOutput = includes([1, 2, 3, 4], "a");
   const targetOutput = false;
 
-  expect(currentOutput).toEqual(targetOutput);
+  expect(currentOutput).toBe(targetOutput);
 });
 
 test("returns true when the target is in array multiple times", () => {
   const currentOutput = includes([1, 2, 2, 3], 2);
   const targetOutput = true;
 
-  expect(currentOutput).toEqual(targetOutput);
+  expect(currentOutput).toBe(targetOutput);
 });
 
 test("returns false for empty array", () => {
-  const currentOutput = includes([]);
+  const currentOutput = includes([], "test");
   const targetOutput = false;
 
-  expect(currentOutput).toEqual(targetOutput);
+  expect(currentOutput).toBe(targetOutput);
 });
 
 test("searches for null", () => {
   const currentOutput = includes(["b", "z", null, "a"], null);
   const targetOutput = true;
 
-  expect(currentOutput).toEqual(targetOutput);
+  expect(currentOutput).toBe(targetOutput);
 });