Manchester | 26-ITP-Jan | Khalidbih| Sprint 1| Data-Groups

Sprint-1/fix/median.js

@@ -6,9 +6,27 @@
 // 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 numbers = list.filter(
+    (n) => typeof n === "number" && Number.isFinite(n)
+  );
+
+  if (numbers.length === 0) {
+    return null;
+  }
+
+  numbers.sort(function (a, b) {
+    return a - b;
+  });
+
+  const middleIndex = Math.floor(numbers.length / 2);
+
+  if (numbers.length % 2 !== 0) {
+    return numbers[middleIndex];
+  }
+
+  return (numbers[middleIndex - 1] + numbers[middleIndex]) / 2;
 }
 
 module.exports = calculateMedian;

Sprint-1/implement/dedupe.js

@@ -1 +1,12 @@
-function dedupe() {}
+function dedupe(arr) {
+  if (!Array.isArray(arr)) return [];
+  const result = [];
+  for (let i = 0; i < arr.length; i++) {
+    if (!result.includes(arr[i])) {
+      result.push(arr[i]);
+    }
+  }
+  return result;
+}
+
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -1,5 +1,8 @@
 const dedupe = require("./dedupe.js");
-/*
+
+describe("dedupe", () => {
+  /* 
+
 Dedupe Array
 
 📖 Dedupe means **deduplicate**
@@ -11,18 +14,38 @@ E.g. dedupe([5, 1, 1, 2, 3, 2, 5, 8]) returns [5, 1, 2, 3, 8]
 E.g. dedupe([1, 2, 1]) returns [1, 2]
 */
 
-// Acceptance Criteria:
+  // Acceptance Criteria:
+
+  // 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", () => {
+    const input = [];
+    const output = dedupe(input);
+    expect(output).toEqual([]);
+  });
+  // Given an array with no duplicates
+  // When passed to the dedupe function
+  // Then it should return a copy of the original array
+  test("array with no duplicates returns a copy", () => {
+    const input = [1, 2, 3];
+    const output = dedupe(input);
+    expect(output).toEqual([1, 2, 3]);
+    expect(output).not.toBe(input);
+  });
 
-// 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 of strings or numbers
+  // When passed to the dedupe function
+  // Then it should return a new array with duplicates removed while preserving the
+  // first occurrence of each element from the original array.
+  test("removes duplicates while preserving first occurrence", () => {
+    const input1 = ["a", "a", "a", "b", "b", "c"];
+    expect(dedupe(input1)).toEqual(["a", "b", "c"]);
 
-// Given an array with no duplicates
-// When passed to the dedupe function
-// Then it should return a copy of the original array
+    const input2 = [5, 1, 1, 2, 3, 2, 5, 8];
+    expect(dedupe(input2)).toEqual([5, 1, 2, 3, 8]);
 
-// 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 
-// first occurrence of each element from the original array.
+    const input3 = [1, 2, 1];
+    expect(dedupe(input3)).toEqual([1, 2]);
+  });
+});

Sprint-1/implement/max.js

@@ -1,4 +1,17 @@
 function findMax(elements) {
+  if (!Array.isArray(elements)) return null;
+
+  let maxValue = -Infinity;
+
+  for (let i = 0; i < elements.length; i++) {
+    if (typeof elements[i] === "number" && isFinite(elements[i])) {
+      if (elements[i] > maxValue) {
+        maxValue = elements[i];
+      }
+    }
+  }
+
+  return maxValue;
 }
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -11,33 +11,56 @@ We have set things up already so that this file can see your function from the o
 */
 
 const findMax = require("./max.js");
+describe("findMax", () => {
+  // Given an empty array
+  // When passed to the max function
+  // Then it should return -Infinity
+  // Delete this test.todo and replace it with a test.
+  test("given an empty array, returns -Infinity", () => {
+    expect(findMax([])).toBe(-Infinity);
+  });
 
-// Given an empty array
-// 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");
+  // Given an array with one number
+  // When passed to the max function
+  // Then it should return that number
+  test("array with one number returns that number", () => {
+    expect(findMax([42])).toBe(42);
+  });
 
-// Given an array with one number
-// When passed to the max function
-// Then it should return that number
+  // Given an array with both positive and negative numbers
+  // When passed to the max function
+  // Then it should return the largest number overall
+  test("array with positive and negative numbers returns the largest number", () => {
+    expect(findMax([-10, 5, 3, -2])).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
+  // Given an array with just negative numbers
+  // When passed to the max function
+  // Then it should return the closest one to zero
+  test("array with only negative numbers returns the closest to zero", () => {
+    expect(findMax([-10, -3, -7])).toBe(-3);
+  });
+  // Given an array with decimal numbers
+  // When passed to the max function
+  // Then it should return the largest decimal number
+  test("array with decimal numbers returns the largest decimal", () => {
+    expect(findMax([1.5, 2.7, 2.6, 0.9])).toBe(2.7);
+  });
+  // 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("array with non-number values ignores them and returns max of numbers", () => {
+    expect(findMax([10, "a", 5, null, 7])).toBe(10);
+  });
 
-// Given an array with just negative numbers
-// When passed to the max function
-// Then it should return the closest one to zero
+  // 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("array with only non-number values returns -Infinity", () => {
+    expect(findMax(["a", null, "b"])).toBe(-Infinity);
+  });
+});
 
-// Given an array with decimal numbers
-// When passed to the max function
-// Then it should return the largest decimal number
-
-// Given an array with non-number values
-// When passed to the max function
-// Then it should return the max and ignore non-numeric values
-
-// 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("array with numeric string ignores it and returns max of numbers", () => {
+  expect(findMax([10, "300", 5, 7])).toBe(10);
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,15 @@
 function sum(elements) {
+  if (!Array.isArray(elements)) return 0;
+
+  let total = 0;
+
+  for (let i = 0; i < elements.length; i++) {
+    if (typeof elements[i] === "number" && isFinite(elements[i])) {
+      total += elements[i];
+    }
+  }
+
+  return total;
 }
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -8,29 +8,48 @@ E.g. sum(['hey', 10, 'hi', 60, 10]), target output: 80 (ignore any non-numerical
 
 const sum = require("./sum.js");
 
-// Acceptance Criteria:
-
-// Given an empty array
-// When passed to the sum function
-// Then it should return 0
-test.todo("given an empty array, returns 0")
-
-// Given an array with just one number
-// When passed to the sum function
-// Then it should return that number
-
-// Given an array containing negative numbers
-// When passed to the sum function
-// Then it should still return the correct total sum
-
-// Given an array with decimal/float numbers
-// When passed to the sum function
-// Then it should return the correct total sum
-
-// 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
-
-// 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
+describe("sum", () => {
+  // Acceptance Criteria:
+
+  // Given an empty array
+  // When passed to the sum function
+  // Then it should return 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("array with 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("array with negative numbers returns correct sum", () => {
+    expect(sum([-2, -3, 5])).toBe(0);
+  });
+
+  // Given an array with decimal/float numbers
+  // When passed to the sum function
+  // Then it should return the correct total sum
+  test("array with decimal numbers returns correct sum", () => {
+    expect(sum([1.5, 2.5, 1])).toBeCloseTo(5);
+  });
+
+  // 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 sums numbers only", () => {
+    expect(sum([10, "a", 5, null, 7])).toBe(22);
+  });
+
+  // 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("returns 0 when array has only non-number values", () => {
+    expect(sum(["a", null, "b"])).toBe(0);
+  });
+});

Sprint-1/refactor/includes.js

@@ -1,12 +1,14 @@
 // 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) {
+  if (!Array.isArray(list)) return false;
+
+  for (const item of list) {
+    if (item === target) {
       return true;
     }
   }
+
   return false;
 }