Merge pull request TheOdinProject#150 from TheOdinProject/jest-solutions

Implement Jest testing platform for all exercises (Solutions branch)

Author: KevinMulhern

caesar/caesar.js

@@ -1,5 +1,26 @@
-const caesar = function() {
+const caesar = function(string, shift) {
+  return string
+    .split("")
+    .map(char => shiftChar(char, shift))
+    .join("");
+};
+
+const codeSet = code => (code < 97 ? 65 : 97);
+
+// this function is just a fancy way of doing % so that it works with negative numbers
+// see this link for details:
+// https://stackoverflow.com/questions/4467539/javascript-modulo-gives-a-negative-result-for-negative-numbers
+const mod = (n, m) => (n % m + m) % m;
+
+const shiftChar = (char, shift) => {
+  const code = char.charCodeAt();
 
+  if ((code >= 65 && code <= 90) || (code >= 97 && code <= 122)) {
+    return String.fromCharCode(
+      mod(code + shift - codeSet(code), 26) + codeSet(code)
+    );
+  }
+  return char;
 };
 
 module.exports = caesar;

calculator/calculator.js

@@ -1,25 +1,41 @@
-const add = function() {
-	
+const add = function(a, b) {
+  return a + b;
 };
 
-const subtract = function() {
-	
+const subtract = function(a, b) {
+  return a - b;
 };
 
-const sum = function() {
-	
+const sum = function(array) {
+  return array.reduce((total, current) => total + current, 0);
 };
 
-const multiply = function() {
+const multiply = function(array) {
+    return array.length
+      ? array.reduce((accumulator, nextItem) => accumulator * nextItem)
+      : 0;
+};
 
+const power = function(a, b) {
+  return Math.pow(a, b);
 };
 
-const power = function() {
-	
+const factorial = function(n) {
+  if (n === 0) return 1;
+  let product = 1;
+  for (let i = n; i > 0; i--) {
+    product *= i;
+  }
+  return product;
 };
 
-const factorial = function() {
-	
+// This is another implementation of Factorial that uses recursion
+// THANKS to @ThirtyThreeB!
+const recursiveFactorial = function(n) {
+  if (n === 0) {
+    return 1;
+  }
+  return n * recursiveFactorial (n-1);
 };
 
 module.exports = {

fibonacci/fibonacci.js

@@ -1,5 +1,14 @@
-const fibonacci = function() {
-
+const fibonacci = function(count) {
+  if (count < 0) return "OOPS";
+  if (count === 0) return 0;
+  let a = 0;
+  let b = 1;
+  for (let i = 1; i < count; i++) {
+    const temp = b;
+    b = a + b;
+    a = temp;
+  }
+  return b;
 };
 
 module.exports = fibonacci;

findTheOldest/findTheOldest.js

@@ -1,5 +1,16 @@
-const findTheOldest = function() {
+const findTheOldest = function(array) {
+  return array.reduce((oldest, currentPerson) => {
+    const oldestAge = getAge(oldest.yearOfBirth, oldest.yearOfDeath)
+    const currentAge = getAge(currentPerson.yearOfBirth, currentPerson.yearOfDeath)
+    return oldestAge < currentAge ? currentPerson : oldest
+  })
+};
 
+const getAge = function(birth, death) {
+  if (!death) {
+    death = new Date().getFullYear();
+  }
+  return death - birth;
 };
 
 module.exports = findTheOldest;

getTheTitles/getTheTitles.js

@@ -1,5 +1,5 @@
-const getTheTitles = function() {
-
+const getTheTitles = function(array) {
+  return array.map(book => book.title)
 };
 
 module.exports = getTheTitles;

helloWorld/helloWorld.js

@@ -1,5 +1,5 @@
 const helloWorld = function() {
-  return ''
+  return 'Hello, World!'
 };
 
 module.exports = helloWorld;

leapYears/leapYears.js

@@ -1,5 +1,5 @@
-const leapYears = function() {
-
+const leapYears = function(year) {
+  return year % 4 === 0 && ( year % 100 !== 0 || year % 400 === 0)
 };
 
 module.exports = leapYears;