Sheffield | 26-ITP-Jan | Karim M'hamdi | Sprint 1 | Module-Data-Groups

Sprint-1/fix/median.js

@@ -6,9 +6,24 @@
 // 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 numbersOnly = list.filter((item) => Number.isFinite(item));
+  const sorted = numbersOnly.sort((a, b) => a - b);
+
+  if (sorted.length === 0) {
+    return null;
+  } else if (sorted.length % 2 === 0) {
+    const mid1 = sorted.length / 2 - 1;
+    const mid2 = sorted.length / 2;
+    const median = (sorted[mid1] + sorted[mid2]) / 2;
+    return median;
+  } else {
+    const middleIndex = Math.floor(sorted.length / 2);
+    const median = sorted[middleIndex];
+    return median;
+  }
 }
 
 module.exports = calculateMedian;

Sprint-1/fix/median.test.js

@@ -13,7 +13,8 @@ describe("calculateMedian", () => {
     { input: [1, 2, 3, 4], expected: 2.5 },
     { input: [1, 2, 3, 4, 5, 6], expected: 3.5 },
   ].forEach(({ input, expected }) =>
-    it(`returns the median for [${input}]`, () => expect(calculateMedian(input)).toEqual(expected))
+    it(`returns the median for [${input}]`, () =>
+      expect(calculateMedian(input)).toEqual(expected))
   );
 
   [
@@ -24,7 +25,8 @@ describe("calculateMedian", () => {
     { input: [110, 20, 0], expected: 20 },
     { input: [6, -2, 2, 12, 14], expected: 6 },
   ].forEach(({ input, expected }) =>
-    it(`returns the correct median for unsorted array [${input}]`, () => expect(calculateMedian(input)).toEqual(expected))
+    it(`returns the correct median for unsorted array [${input}]`, () =>
+      expect(calculateMedian(input)).toEqual(expected))
   );
 
   it("doesn't modify the input array [3, 1, 2]", () => {
@@ -33,8 +35,17 @@ describe("calculateMedian", () => {
     expect(list).toEqual([3, 1, 2]);
   });
 
-  [ 'not an array', 123, null, undefined, {}, [], ["apple", null, undefined] ].forEach(val =>
-    it(`returns null for non-numeric array (${val})`, () => expect(calculateMedian(val)).toBe(null))
+  [
+    "not an array",
+    123,
+    null,
+    undefined,
+    {},
+    [],
+    ["apple", null, undefined],
+  ].forEach((val) =>
+    it(`returns null for non-numeric array (${val})`, () =>
+      expect(calculateMedian(val)).toBe(null))
   );
 
   [
@@ -45,6 +56,7 @@ describe("calculateMedian", () => {
     { input: [3, "apple", 1, null, 2, undefined, 4], expected: 2.5 },
     { input: ["banana", 5, 3, "apple", 1, 4, 2], expected: 3 },
   ].forEach(({ input, expected }) =>
-    it(`filters out non-numeric values and calculates the median for [${input}]`, () => expect(calculateMedian(input)).toEqual(expected))
+    it(`filters out non-numeric values and calculates the median for [${input}]`, () =>
+      expect(calculateMedian(input)).toEqual(expected))
   );
 });

Sprint-1/implement/dedupe.js

@@ -1 +1,13 @@
-function dedupe() {}
+function dedupe(array) {
+  let seen = new Set();
+  let result = [];
+    for (let item of array) {
+        if (!seen.has(item)) {
+            seen.add(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");
+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("given an array with no duplicates, it returns the same array", () => {
+  expect(dedupe([1, 2, 3])).toEqual([1, 2, 3]);
+});
 
 // 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("removes duplicates and keeps 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]);
+});
+

Sprint-1/implement/max.js

@@ -1,4 +1,22 @@
 function findMax(elements) {
+  let max = -Infinity;
+  let foundNumber = false;
+
+  for (let i = 0; i < elements.length; i++) {
+    if (Number.isFinite(elements[i])) {
+      foundNumber = true;
+
+      if (elements[i] > max) {
+        max = elements[i];
+      }
+    }
+  }
+
+  if (!foundNumber) {
+    return null;
+  }
+
+  return max;
 }
 
-module.exports = findMax;
+module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -16,28 +16,48 @@ 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 null", () => {
+  expect(findMax([])).toBe(null);
+});
 
 // 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([7])).toBe(7);
+});
 
 // 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 positive and negative numbers, returns the largest number", () => {
+  expect(findMax([-10, 0, 5, -3, 8])).toBe(8);
+});
 
 // Given an array with just negative numbers
 // When passed to the max function
 // Then it should return the closest one to zero
+test("given only negative numbers, returns the largest negative number", () => {
+  expect(findMax([-10, -4, -2, -30])).toBe(-2);
+});
 
 // Given an array with decimal numbers
 // When passed to the max function
 // Then it should return the largest decimal number
+test("given decimal numbers, returns the largest decimal number", () => {
+  expect(findMax([1.2, 3.7, 2.5])).toBe(3.7);
+});
 
 // 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("ignores non-number values and returns the max", () => {
+  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 only non-number values, returns null", () => {
+  expect(findMax(["hey", "hi", null, undefined, NaN])).toBe(null);
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,11 @@
 function sum(elements) {
+  let sum = 0;
+  for (let i = 0; i < elements.length; i++) {
+    if (Number.isFinite(elements[i])) {
+      sum += elements[i];
+    }
+  }
+  return sum;
 }
 
 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")
+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 one number, returns 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
+test("given negative numbers, returns the correct total", () => {
+  expect(sum([-10, -3, -2])).toBe(-15);
+});
 
 // Given an array with decimal/float numbers
 // When passed to the sum function
 // Then it should return the correct total sum
+test("given decimal numbers, returns the correct total", () => {
+  expect(sum([1.5, 2.5, 3])).toBe(7);
+});
 
 // 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("ignores non-number values and returns the sum", () => {
+  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 only non-number values, returns 0", () => {
+  expect(sum(["hey", "hi", null, undefined, NaN])).toBe(0);
+});
+

Sprint-1/refactor/includes.js

@@ -1,8 +1,7 @@
 // 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];
+  for (const element of list) {
     if (element === target) {
       return true;
     }