Merge branch 'main' into fix_typo_readme

.circleci/config.yml

@@ -0,0 +1,20 @@
+version: 2.1
+
+orbs:
+  node: circleci/node@5.1.0
+
+jobs:
+  test-solutions:
+    executor: node/default
+    steps: 
+      - checkout
+      - node/install-packages:
+          pkg-manager: npm
+      - run:
+          command: npm run test solution
+          name: Run tests in **/solution/*.spec.js
+
+workflows:
+  test-solutions:
+    jobs:
+      - test-solutions

01_helloWorld/solution/helloWorld-solution.js

@@ -0,0 +1,5 @@
+const helloWorld = function () {
+  return "Hello, World!";
+};
+
+module.exports = helloWorld;

01_helloWorld/solution/helloWorld-solution.spec.js

@@ -0,0 +1,7 @@
+const helloWorld = require('./helloWorld-solution');
+
+describe('Hello World', function () {
+  test('says "Hello, World!"', function () {
+    expect(helloWorld()).toEqual('Hello, World!');
+  });
+});

02_repeatString/solution/repeatString-solution.js

@@ -0,0 +1,10 @@
+const repeatString = function (word, times) {
+  if (times < 0) return "ERROR";
+  let string = "";
+  for (let i = 0; i < times; i++) {
+    string += word;
+  }
+  return string;
+};
+
+module.exports = repeatString;

02_repeatString/solution/repeatString-solution.spec.js

@@ -0,0 +1,39 @@
+const repeatString = require('./repeatString-solution');
+
+describe('repeatString', () => {
+  test('repeats the string', () => {
+    expect(repeatString('hey', 3)).toEqual('heyheyhey');
+  });
+  test('repeats the string many times', () => {
+    expect(repeatString('hey', 10)).toEqual('heyheyheyheyheyheyheyheyheyhey');
+  });
+  test('repeats the string 1 times', () => {
+    expect(repeatString('hey', 1)).toEqual('hey');
+  });
+  test('repeats the string 0 times', () => {
+    expect(repeatString('hey', 0)).toEqual('');
+  });
+  test('returns ERROR with negative numbers', () => {
+    expect(repeatString('hey', -1)).toEqual('ERROR');
+  });
+  test('repeats the string a random amount of times', function () {
+    /*The number is generated by using Math.random to get a value from between
+    0 to 1, when this is multiplied by 1000 and rounded down with Math.floor it 
+    equals a number between 0 to 999 (this number will change everytime you run
+    the test).*/
+
+    // DO NOT use Math.floor(Math.random() * 1000) in your code,
+    // this test generates a random number, then passes it into your code with a function parameter.
+    // If this doesn't make sense, you should go read about functions here: https://www.theodinproject.com/paths/foundations/courses/foundations/lessons/fundamentals-part-3
+    const number = Math.floor(Math.random() * 1000);
+    /*The .match(/((hey))/g).length is a regex that will count the number of heys
+    in the result, which if your function works correctly will equal the number that
+    was randomaly generated. */
+    expect(repeatString('hey', number).match(/((hey))/g).length).toEqual(
+      number
+    );
+  });
+  test('works with blank strings', () => {
+    expect(repeatString('', 10)).toEqual('');
+  });
+});

03_reverseString/README.md

@@ -6,7 +6,5 @@ Pretty simple, write a function called `reverseString` that returns its input, r
 reverseString('hello there') // returns 'ereht olleh'
 ```
 
-You will notice in this exercise that there are multiple tests, after making the first one pass, enable the others one by one by deleting the `.skip` in front the `test.skip()` function.
-
 ## Hints
 Strings in JavaScript cannot be reversed directly so you're going to have to split it into something else first.. do the reversal and then join it back together into a string.

03_reverseString/solution/reverseString-solution.js

@@ -0,0 +1,5 @@
+const reverseString = function (string) {
+  return string.split("").reverse().join("");
+};
+
+module.exports = reverseString;

03_reverseString/solution/reverseString-solution.spec.js

@@ -0,0 +1,18 @@
+const reverseString = require('./reverseString-solution');
+
+describe('reverseString', () => {
+  test('reverses single word', () => {
+    expect(reverseString('hello')).toEqual('olleh');
+  });
+
+  test('reverses multiple words', () => {
+    expect(reverseString('hello there')).toEqual('ereht olleh');
+  });
+
+  test('works with numbers and punctuation', () => {
+    expect(reverseString('123! abc!')).toEqual('!cba !321');
+  });
+  test('works with blank strings', () => {
+    expect(reverseString('')).toEqual('');
+  });
+});

04_removeFromArray/solution/removeFromArray-solution.js

@@ -0,0 +1,28 @@
+// we have 2 solutions here, an easier one and a more advanced one.
+// The easiest way to get an array of the rest of the arguments that are passed to a function
+// is using the rest operator. If this is unfamiliar to you look it up!
+const removeFromArray = function (array, ...args) {
+  // create a new empty array
+  const newArray = [];
+  // use forEach to go through the array
+  array.forEach((item) => {
+    // push every element into the new array
+    // UNLESS it is included in the function arguments
+    // so we create a new array with every item, except those that should be removed
+    if (!args.includes(item)) {
+      newArray.push(item);
+    }
+  });
+  // and return that array
+  return newArray;
+};
+
+// A simpler, but more advanced way to do it is to use the 'filter' function,
+// which basically does what we did with the forEach above.
+
+// var removeFromArray = function(array, ...args) {
+//   return array.filter(val => !args.includes(val))
+// }
+//
+
+module.exports = removeFromArray;

04_removeFromArray/solution/removeFromArray-solution.spec.js

@@ -0,0 +1,25 @@
+const removeFromArray = require('./removeFromArray-solution');
+
+describe('removeFromArray', () => {
+  test('removes a single value', () => {
+    expect(removeFromArray([1, 2, 3, 4], 3)).toEqual([1, 2, 4]);
+  });
+  test('removes multiple values', () => {
+    expect(removeFromArray([1, 2, 3, 4], 3, 2)).toEqual([1, 4]);
+  });
+  test('ignores non present values', () => {
+    expect(removeFromArray([1, 2, 3, 4], 7, 'tacos')).toEqual([1, 2, 3, 4]);
+  });
+  test('ignores non present values, but still works', () => {
+    expect(removeFromArray([1, 2, 3, 4], 7, 2)).toEqual([1, 3, 4]);
+  });
+  test('can remove all values', () => {
+    expect(removeFromArray([1, 2, 3, 4], 1, 2, 3, 4)).toEqual([]);
+  });
+  test('works with strings', () => {
+    expect(removeFromArray(['hey', 2, 3, 'ho'], 'hey', 3)).toEqual([2, 'ho']);
+  });
+  test('only removes same type', () => {
+    expect(removeFromArray([1, 2, 3], '1', 3)).toEqual([1, 2]);
+  });
+});

05_sumAll/solution/sumAll-solution.js

@@ -0,0 +1,16 @@
+const sumAll = function (min, max) {
+  if (!Number.isInteger(min) || !Number.isInteger(max)) return "ERROR";
+  if (min < 0 || max < 0) return "ERROR";
+  if (min > max) {
+    const temp = min;
+    min = max;
+    max = temp;
+  }
+  let sum = 0;
+  for (let i = min; i < max + 1; i++) {
+    sum += i;
+  }
+  return sum;
+};
+
+module.exports = sumAll;

05_sumAll/solution/sumAll-solution.spec.js

@@ -0,0 +1,25 @@
+const sumAll = require('./sumAll-solution');
+
+describe('sumAll', () => {
+  test('sums numbers within the range', () => {
+    expect(sumAll(1, 4)).toEqual(10);
+  });
+  test('works with large numbers', () => {
+    expect(sumAll(1, 4000)).toEqual(8002000);
+  });
+  test('works with larger number first', () => {
+    expect(sumAll(123, 1)).toEqual(7626);
+  });
+  test('returns ERROR with negative numbers', () => {
+    expect(sumAll(-10, 4)).toEqual('ERROR');
+  });
+  test('returns ERROR with non-integer parameters', () => {
+    expect(sumAll(2.5, 4)).toEqual('ERROR');
+  });
+  test('returns ERROR with non-number parameters', () => {
+    expect(sumAll(10, '90')).toEqual('ERROR');
+  });
+  test('returns ERROR with non-number parameters', () => {
+    expect(sumAll(10, [90, 1])).toEqual('ERROR');
+  });
+});

06_leapYears/solution/leapYears-solution.js

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

06_leapYears/solution/leapYears-solution.spec.js

@@ -0,0 +1,22 @@
+const leapYears = require('./leapYears-solution');
+
+describe('leapYears', () => {
+  test('works with non century years', () => {
+    expect(leapYears(1996)).toBe(true);
+  });
+  test('works with non century years', () => {
+    expect(leapYears(1997)).toBe(false);
+  });
+  test('works with ridiculously futuristic non century years', () => {
+    expect(leapYears(34992)).toBe(true);
+  });
+  test('works with century years', () => {
+    expect(leapYears(1900)).toBe(false);
+  });
+  test('works with century years', () => {
+    expect(leapYears(1600)).toBe(true);
+  });
+  test('works with century years', () => {
+    expect(leapYears(700)).toBe(false);
+  });
+});

07_tempConversion/solution/tempConversion-solution.js

@@ -0,0 +1,12 @@
+const convertToCelsius = function (fahrenheit) {
+  return Math.round((fahrenheit - 32) * (5 / 9) * 10) / 10;
+};
+
+const convertToFahrenheit = function (celsius) {
+  return Math.round(((celsius * 9) / 5 + 32) * 10) / 10;
+};
+
+module.exports = {
+  convertToCelsius,
+  convertToFahrenheit,
+};

07_tempConversion/solution/tempConversion-solution.spec.js

@@ -0,0 +1,28 @@
+const {
+  convertToCelsius,
+  convertToFahrenheit,
+} = require('./tempConversion-solution');
+
+describe('convertToCelsius', () => {
+  test('works', () => {
+    expect(convertToCelsius(32)).toEqual(0);
+  });
+  test('rounds to 1 decimal', () => {
+    expect(convertToCelsius(100)).toEqual(37.8);
+  });
+  test('works with negatives', () => {
+    expect(convertToCelsius(-100)).toEqual(-73.3);
+  });
+});
+
+describe('convertToFahrenheit', () => {
+  test('works', () => {
+    expect(convertToFahrenheit(0)).toEqual(32);
+  });
+  test('rounds to 1 decimal', () => {
+    expect(convertToFahrenheit(73.2)).toEqual(163.8);
+  });
+  test('works with negatives', () => {
+    expect(convertToFahrenheit(-10)).toEqual(14);
+  });
+});

08_calculator/solution/calculator-solution.js

@@ -0,0 +1,48 @@
+const add = function (a, b) {
+  return a + b;
+};
+
+const subtract = function (a, b) {
+  return a - b;
+};
+
+const sum = function (array) {
+  return array.reduce((total, current) => total + current, 0);
+};
+
+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 factorial = function (n) {
+  if (n === 0) return 1;
+  let product = 1;
+  for (let i = n; i > 0; i--) {
+    product *= i;
+  }
+  return product;
+};
+
+// 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 = {
+  add,
+  subtract,
+  sum,
+  multiply,
+  power,
+  factorial,
+};

08_calculator/solution/calculator-solution.spec.js

@@ -0,0 +1,77 @@
+const calculator = require('./calculator-solution');
+
+describe('add', () => {
+  test('adds 0 and 0', () => {
+    expect(calculator.add(0, 0)).toBe(0);
+  });
+
+  test('adds 2 and 2', () => {
+    expect(calculator.add(2, 2)).toBe(4);
+  });
+
+  test('adds positive numbers', () => {
+    expect(calculator.add(2, 6)).toBe(8);
+  });
+});
+
+describe('subtract', () => {
+  test('subtracts numbers', () => {
+    expect(calculator.subtract(10, 4)).toBe(6);
+  });
+});
+
+describe('sum', () => {
+  test('computes the sum of an empty array', () => {
+    expect(calculator.sum([])).toBe(0);
+  });
+
+  test('computes the sum of an array of one number', () => {
+    expect(calculator.sum([7])).toBe(7);
+  });
+
+  test('computes the sum of an array of two numbers', () => {
+    expect(calculator.sum([7, 11])).toBe(18);
+  });
+
+  test('computes the sum of an array of many numbers', () => {
+    expect(calculator.sum([1, 3, 5, 7, 9])).toBe(25);
+  });
+});
+
+describe('multiply', () => {
+  test('multiplies two numbers', () => {
+    expect(calculator.multiply([2, 4])).toBe(8);
+  });
+
+  test('multiplies several numbers', () => {
+    expect(calculator.multiply([2, 4, 6, 8, 10, 12, 14])).toBe(645120);
+  });
+});
+
+describe('power', () => {
+  test('raises one number to the power of another number', () => {
+    expect(calculator.power(4, 3)).toBe(64); // 4 to third power is 64
+  });
+});
+
+describe('factorial', () => {
+  test('computes the factorial of 0', () => {
+    expect(calculator.factorial(0)).toBe(1); // 0! = 1
+  });
+
+  test('computes the factorial of 1', () => {
+    expect(calculator.factorial(1)).toBe(1);
+  });
+
+  test('computes the factorial of 2', () => {
+    expect(calculator.factorial(2)).toBe(2);
+  });
+
+  test('computes the factorial of 5', () => {
+    expect(calculator.factorial(5)).toBe(120);
+  });
+
+  test('computes the factorial of 10', () => {
+    expect(calculator.factorial(10)).toBe(3628800);
+  });
+});

09_palindromes/solution/palindromes-solution.js

@@ -0,0 +1,6 @@
+const palindromes = function (string) {
+  const processedString = string.toLowerCase().replace(/[^a-z]/g, "");
+  return processedString.split("").reverse().join("") == processedString;
+};
+
+module.exports = palindromes;

09_palindromes/solution/palindromes-solution.spec.js

@@ -0,0 +1,24 @@
+const palindromes = require('./palindromes-solution');
+
+describe('palindromes', () => {
+  test('works with single words', () => {
+    expect(palindromes('racecar')).toBe(true);
+  });
+  test('works with punctuation ', () => {
+    expect(palindromes('racecar!')).toBe(true);
+  });
+  test('works with upper-case letters ', () => {
+    expect(palindromes('Racecar!')).toBe(true);
+  });
+  test('works with multiple words', () => {
+    expect(palindromes('A car, a man, a maraca.')).toBe(true);
+  });
+  test('works with multiple words', () => {
+    expect(palindromes('Animal loots foliated detail of stool lamina.')).toBe(
+      true
+    );
+  });
+  test("doesn't just always return true", () => {
+    expect(palindromes('ZZZZ car, a man, a maraca.')).toBe(false);
+  });
+});

10_fibonacci/solution/fibonacci-solution.js

@@ -0,0 +1,14 @@
+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;

10_fibonacci/solution/fibonacci-solution.spec.js

@@ -0,0 +1,31 @@
+const fibonacci = require('./fibonacci-solution');
+
+describe('fibonacci', () => {
+  test('4th fibonacci number is 3', () => {
+    expect(fibonacci(4)).toBe(3);
+  });
+  test('6th fibonacci number is 8', () => {
+    expect(fibonacci(6)).toBe(8);
+  });
+  test('10th fibonacci number is 55', () => {
+    expect(fibonacci(10)).toBe(55);
+  });
+  test('15th fibonacci number is 610', () => {
+    expect(fibonacci(15)).toBe(610);
+  });
+  test('25th fibonacci number is 75025', () => {
+    expect(fibonacci(25)).toBe(75025);
+  });
+  test("doesn't accept negatives", () => {
+    expect(fibonacci(-25)).toBe('OOPS');
+  });
+  test('DOES accept strings', () => {
+    expect(fibonacci('1')).toBe(1);
+  });
+  test('DOES accept strings', () => {
+    expect(fibonacci('2')).toBe(1);
+  });
+  test('DOES accept strings', () => {
+    expect(fibonacci('8')).toBe(21);
+  });
+});

11_getTheTitles/solution/getTheTitles-solution.js

@@ -0,0 +1,5 @@
+const getTheTitles = function (array) {
+  return array.map((book) => book.title);
+};
+
+module.exports = getTheTitles;

11_getTheTitles/solution/getTheTitles-solution.spec.js

@@ -0,0 +1,18 @@
+const getTheTitles = require('./getTheTitles-solution');
+
+describe('getTheTitles', () => {
+  const books = [
+    {
+      title: 'Book',
+      author: 'Name',
+    },
+    {
+      title: 'Book2',
+      author: 'Name2',
+    },
+  ];
+
+  test('gets titles', () => {
+    expect(getTheTitles(books)).toEqual(['Book', 'Book2']);
+  });
+});

12_findTheOldest/solution/findTheOldest-solution.js

@@ -0,0 +1,19 @@
+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;

12_findTheOldest/solution/findTheOldest-solution.spec.js

@@ -0,0 +1,62 @@
+const findTheOldest = require('./findTheOldest-solution');
+
+describe('findTheOldest', () => {
+  test('finds the oldest person!', () => {
+    const people = [
+      {
+        name: 'Carly',
+        yearOfBirth: 1942,
+        yearOfDeath: 1970,
+      },
+      {
+        name: 'Ray',
+        yearOfBirth: 1962,
+        yearOfDeath: 2011,
+      },
+      {
+        name: 'Jane',
+        yearOfBirth: 1912,
+        yearOfDeath: 1941,
+      },
+    ];
+    expect(findTheOldest(people).name).toBe('Ray');
+  });
+  test('finds the oldest person if someone is still living', () => {
+    const people = [
+      {
+        name: 'Carly',
+        yearOfBirth: 2018,
+      },
+      {
+        name: 'Ray',
+        yearOfBirth: 1962,
+        yearOfDeath: 2011,
+      },
+      {
+        name: 'Jane',
+        yearOfBirth: 1912,
+        yearOfDeath: 1941,
+      },
+    ];
+    expect(findTheOldest(people).name).toBe('Ray');
+  });
+  test('finds the oldest person if the OLDEST is still living', () => {
+    const people = [
+      {
+        name: 'Carly',
+        yearOfBirth: 1066,
+      },
+      {
+        name: 'Ray',
+        yearOfBirth: 1962,
+        yearOfDeath: 2011,
+      },
+      {
+        name: 'Jane',
+        yearOfBirth: 1912,
+        yearOfDeath: 1941,
+      },
+    ];
+    expect(findTheOldest(people).name).toBe('Carly');
+  });
+});

README.md

@@ -10,17 +10,22 @@ If you have a suggestion to improve an exercise, an idea for a new exercise, or
 
 ## How To Use These Exercises
 
-1. Fork and clone this repository. To learn how to fork a repository, see the GitHub documentation on how to [fork a repo](https://docs.github.com/en/get-started/quickstart/fork-a-repo). 
-    * Copies of repositories on your machine are called clones. If you need help cloning to your local environment you can learn how from the GitHub documentation on [cloning a repository](https://docs.github.com/en/github/creating-cloning-and-archiving-repositories/cloning-a-repository-from-github/cloning-a-repository).
+
+1. Fork and clone this repository. To learn how to fork a repository, see the GitHub documentation on how to [fork a repo](https://docs.github.com/en/get-started/quickstart/fork-a-repo).
+   - Copies of repositories on your machine are called clones. If you need help cloning to your local environment you can learn how from the GitHub documentation on [cloning a repository](https://docs.github.com/en/github/creating-cloning-and-archiving-repositories/cloning-a-repository-from-github/cloning-a-repository).
 2. Before you start working on any exercises, you should first ensure you have the following installed:
-    * **NPM**. You should have installed NPM already in our [Installing Node.js](https://www.theodinproject.com/lessons/foundations-installing-node-js) lesson. Just in case you need to check, type `npm --version` in your terminal. If you get back `Command 'npm' not found, but can be installed with:`, **do not follow the instructions in the terminal** to install with `apt-get` as this causes permission issues. Instead, go back to the installation lesson and install Node with NVM by following the instructions there.
-    * **Jest**. After cloning this repository to your local machine and installing NPM, go into the newly created directory (`cd javascript-exercises`) and run `npm install`. This will install Jest and set up the testing platform based on our preconfigured settings.
-3. Each exercise includes 3 files: a markdown file with a description of the task, an empty (or mostly empty) JavaScript file, and a set of tests. To complete an exercise, you'll need to go to the exercise directory with `cd exerciseName` in the terminal and run `npm test exerciseName.spec.js`. This should run the test file and show you the output.
-    * When you first run a test, it will fail. This is by design! You must open the exercise file and write the code needed to get the test to pass. 
+   - **NPM**. You should have installed NPM already in our [Installing Node.js](https://www.theodinproject.com/paths/foundations/courses/foundations/lessons/installing-node-js) lesson. Just in case you need to check, type `npm --version` in your terminal. If you get back `Command 'npm' not found, but can be installed with:`, **do not follow the instructions in the terminal** to install with `apt-get` as this causes permission issues. Instead, go back to the installation lesson and install Node with NVM by following the instructions there.
+   - **Jest**. After cloning this repository to your local machine and installing NPM, go into the newly created directory (`cd javascript-exercises`) and run `npm install`. This will install Jest and set up the testing platform based on our preconfigured settings.
+3. Each exercise includes the following:
+
+   - A markdown file with a description of the task, an empty (or mostly empty) JavaScript file, and a set of tests.
+   - A `solutions` directory that contains a solution and the same test file with all of the tests unskipped.
+
+   To complete an exercise, you'll need to go to the exercise directory with `cd exerciseName` in the terminal and run `npm test exerciseName.spec.js`. This should run the test file and show you the output. When you first run a test, it will fail. This is by design! You must open the exercise file and write the code needed to get the test to pass.
 4. Some of the exercises have test conditions defined in their spec file as `test.skip` compared to `test`. This is purposeful. After you pass one `test`, you will change the next `test.skip` to `test` and test your code again. You'll do this until all conditions are satisfied. **All tests must pass at the same time**, and you should not have any `test.skip` instances by the time you finish an exercise.
-5. Once you successfully finish an exercise, check TOP's `solutions` branch to compare it with yours. 
-   * You should not be checking the solution for an exercise until you finish it!
-   * Keep in mind that TOP's solution is not the only solution. Generally as long as all of the tests pass, your solution should be fine.
+5. Once you successfully finish an exercise, check the `solutions` directory within each exercise to compare it with yours.
+   - You should not be checking the solution for an exercise until you finish it!
+   - Keep in mind that TOP's solution is not the only solution. Generally as long as all of the tests pass, your solution should be fine.
 6. Do not submit your solutions to this repo, as any PRs that do so will be closed without merging.
 
 **Note**: Due to the way Jest handles failed tests, it may return an exit code of 1 if any tests fail. NPM will interpret this as an error and you may see some `npm ERR!` messages after Jest runs. You can ignore these, or run your test with `npm test exerciseName.spec.js --silent` to supress the errors.

archive/archived_caesar/solution/caesar-solution.js

@@ -0,0 +1,26 @@
+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;

archive/archived_caesar/solution/caesar-solution.spec.js

@@ -0,0 +1,23 @@
+const caesar = require('./caesar-solution');
+
+test('works with single letters', () => {
+  expect(caesar('A', 1)).toBe('B');
+});
+test('works with words', () => {
+  expect(caesar('Aaa', 1)).toBe('Bbb');
+});
+test('works with phrases', () => {
+  expect(caesar('Hello, World!', 5)).toBe('Mjqqt, Btwqi!');
+});
+test('works with negative shift', () => {
+  expect(caesar('Mjqqt, Btwqi!', -5)).toBe('Hello, World!');
+});
+test('wraps', () => {
+  expect(caesar('Z', 1)).toBe('A');
+});
+test('works with large shift factors', () => {
+  expect(caesar('Hello, World!', 75)).toBe('Ebiil, Tloia!');
+});
+test('works with large negative shift factors', () => {
+  expect(caesar('Hello, World!', -29)).toBe('Ebiil, Tloia!');
+});

archive/archived_pigLatin/solution/pigLatin-solution.js

@@ -0,0 +1,21 @@
+const pigLatin = function (string) {
+  return string
+    .split(" ")
+    .map((word) => {
+      const index = firstVowelIndex(word);
+      const beginning = word.slice(0, index);
+      const ending = word.slice(index);
+      return `${ending}${beginning}ay`;
+    })
+    .join(" ");
+};
+
+const firstVowelIndex = function (string) {
+  const vowels = string.match(/[aeiou]/g);
+  if (vowels[0] == "u" && string[string.indexOf(vowels[0]) - 1] == "q") {
+    return string.indexOf(vowels[1]);
+  }
+  return string.indexOf(vowels[0]);
+};
+
+module.exports = pigLatin;

archive/archived_pigLatin/solution/pigLatin-solution.spec.js

@@ -0,0 +1,56 @@
+const pigLatin = require('./pigLatin-solution');
+
+//  Topics
+
+//  * modules
+//  * strings
+
+//  Pig Latin
+
+// Pig Latin is a made-up children's language that's intended to be confusing. test obeys a few simple rules (below) but when test's spoken quickly test's really difficult for non-children (and non-native speakers) to understand.
+
+// Rule 1: If a word begins with a vowel sound, add an "ay" sound to the end of the word.
+
+// Rule 2: If a word begins with a consonant sound, move test to the end of the word, and then add an "ay" sound to the end of the word.
+
+// (There are a few more rules for edge cases, and there are regional variants too, but that should be enough to understand the tests.)
+
+// See https://en.wikipedia.org/wiki/Pig_Latin for more details.
+
+describe('translate', () => {
+  test('translates a word beginning with a vowel', () => {
+    expect(pigLatin('apple')).toBe('appleay');
+  });
+
+  test('translates a word beginning with a consonant', () => {
+    expect(pigLatin('banana')).toBe('ananabay');
+  });
+
+  test('translates a word beginning with two consonants', () => {
+    expect(pigLatin('cherry')).toBe('errychay');
+  });
+
+  test('translates two words', () => {
+    expect(pigLatin('eat pie')).toBe('eatay iepay');
+  });
+
+  test('translates a word beginning with three consonants', () => {
+    expect(pigLatin('three')).toBe('eethray');
+  });
+
+  test('counts "sch" as a single phoneme', () => {
+    expect(pigLatin('school')).toBe('oolschay');
+  });
+
+  test('counts "qu" as a single phoneme', () => {
+    expect(pigLatin('quiet')).toBe('ietquay');
+  });
+
+  test('counts "qu" as a consonant even when its preceded by a consonant', () => {
+    expect(pigLatin('square')).toBe('aresquay');
+  });
+
+  test('translates many words', () => {
+    expect(pigLatin('the quick brown fox')).toBe('ethay ickquay ownbray oxfay');
+  });
+});

archive/archived_snakeCase/solution/snakeCase-solution.js

@@ -0,0 +1,19 @@
+const snakeCase = function (string) {
+  // wtf case
+  string = string.replace(/\.\./g, " ");
+
+  // this splits up camelcase IF there are no spaces in the word
+  if (string.indexOf(" ") < 0) {
+    string = string.replace(/([A-Z])/g, " $1");
+  }
+
+  return string
+    .trim()
+    .toLowerCase()
+    .replace(/[,\?\.]/g, "")
+    .replace(/\-/g, " ")
+    .split(" ")
+    .join("_");
+};
+
+module.exports = snakeCase;

archive/archived_snakeCase/solution/snakeCase-solution.spec.js

@@ -0,0 +1,26 @@
+const snakeCase = require('./snakeCase-solution');
+
+describe('snakeCase', () => {
+  test('works with simple lowercased phrases', () => {
+    expect(snakeCase('hello world')).toEqual('hello_world');
+  });
+  test('works with Caps and punctuation', () => {
+    expect(snakeCase('Hello, World???')).toEqual('hello_world');
+  });
+  test('works with longer phrases', () => {
+    expect(snakeCase('This is the song that never ends....')).toEqual(
+      'this_is_the_song_that_never_ends'
+    );
+  });
+  test('works with camel case', () => {
+    expect(snakeCase('snakeCase')).toEqual('snake_case');
+  });
+  test('works with kebab case', () => {
+    expect(snakeCase('snake-case')).toEqual('snake_case');
+  });
+  test('works with WTF case', () => {
+    expect(snakeCase('SnAkE..CaSe..Is..AwEsOmE')).toEqual(
+      'snake_case_is_awesome'
+    );
+  });
+});