London | 26-May-ITP | Yonatan Teklemariam | Sprint 1 | exercises

Sprint-1/fix/median.js

@@ -6,9 +6,23 @@
 // 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;
+  // this line of code checks if the list is an array and if it has any elements. If not, it returns null
+  if (!Array.isArray(list) || list.length === 0) {
+    return null;
+  }
+  // this line of code filters the list to only include numbers. And if there are no numbers in the list, it returns null
+  const numbersOnly = list.filter((item) => typeof item === "number");
+  if (numbersOnly.length === 0) {
+    return null;
+  }
+  // this line of code sorts the numbers in ascending order and calculates the median based on whether the length of the sorted array is even or odd
+  const sorted = [...numbersOnly].sort((a, b) => a - b);
+  const middleIndex = Math.floor(sorted.length / 2);
+  if (sorted.length % 2 === 0) {
+    const median = (sorted[middleIndex - 1] + sorted[middleIndex]) / 2;
+    return median;
+  }
+  return sorted[middleIndex];
 }
 
 module.exports = calculateMedian;

Sprint-1/implement/dedupe.js

@@ -1 +1,20 @@
-function dedupe() {}
+function dedupe(arr) {
+  if (!Array.isArray(arr)) {
+    return null;
+  }
+
+  const newVersion = new Set(arr);
+
+  // If no duplicates, return the original array
+  if (newVersion.size === arr.length) {
+    return arr;
+  }
+
+  // Otherwise return the deduped array
+  const newArray = [...newVersion];
+  return newArray;
+}
+
+console.log(dedupe([1, 2, 3]));
+console.log(dedupe([10, 30, 20, 50, 20, 10]));
+console.log(dedupe(5, 1, 1, 2, 3, 2, 5, 8));

Sprint-1/implement/dedupe.test.js

@@ -24,5 +24,8 @@ 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 
+// Then it should return a new array with duplicates removed while preserving the
 // first occurrence of each element from the original array.
+/*
+
+*/

Sprint-1/implement/max.js

@@ -1,4 +1,20 @@
 function findMax(elements) {
+  let max = -Infinity;
+  for (const value of elements) {
+    if (typeof value === "number" && !Number.isNaN(value)) {
+      if (value > max) {
+        max = value;
+      }
+    }
+  }
+  return max;
 }
+console.log(findMax([])); // -Infinity
+console.log(findMax([42])); // 42
+console.log(findMax([-10, 20, -5, 7])); // 20
+console.log(findMax([-50, -3, -100])); // -3
+console.log(findMax([1.5, 3.2, 2.8])); // 3.2
+console.log(findMax(["hey", 10, "hi", 60, 10])); // 60
+console.log(findMax(["a", {}, null])); // -Infinity
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -16,28 +16,43 @@ 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, it should return -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, it should return that number", () => {
+  expect(findMax([12])).toBe(12);
+});
 // 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, it should return the largest overall", () => {
+  expect(findMax([99, 86])).toBe(99);
+});
 // 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 negative numbers, it should return the closest number to zero", () => {
+  expect(findMax([-14, -24, -1120, -7])).toBe(-7);
+});
 // 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, it should return the largest decimal number", () => {
+  expect(findMax([0.8, 1.3, 1.79, 1.8])).toBe(1.8);
+});
 // 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-numeric values, it should return the max without non-numeric values", () => {
+  expect(findMax(["yay", 12, "yey", 7, "yonatan", 31])).toBe(31);
+});
 // 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, it should return the least suprising value given", () => {
+  expect(findMax(["f", "r", {}, null, "$"])).toBe(-Infinity);
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,11 @@
 function sum(elements) {
+  let total = 0;
+  for (const myNum of elements) {
+    if (typeof myNum === "number" && !Number.isNaN(myNum)) {
+      total += myNum;
+    }
+  }
+  return total;
 }
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -9,28 +9,40 @@ 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")
+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([54])).toBe(54);
+});
 // 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 negative numbers, returns the correct total sum", () => {
+  expect(sum([-25, -100, 75])).toBe(-50);
+});
 // 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([1.5, 2.5, 3.1])).toBe(7.1);
+});
 // 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 non-number values, returns the sum of the numerical elements", () => {
+  expect(sum(["yoyo", 32, 10, "aha"])).toBe(42);
+});
 // 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-numeric values, returns 0", () => {
+  expect(sum(["£", "&", null, undefined, "abc"])).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;
     }