Javascript Classes

Let's put our knowledge of classes to practice! In this assignment, you will create javascript objects that model real life objects using classes as a blueprint

Getting Started

Fork this repo
git clone <repo-url>
cd into directory
Make this a yarn project: yarn init
Install jest: yarn add --dev jest
Update package.json to have test scripts:

{
  "name": "my-project",
  "version": "1.0.0",
  ...
  // add the following key-value pair
  "scripts": {
      "test": "jest",     
      "test:watch": "jest --watch",
      "test:coverage": "jest --coverage",
  },
  ...
}

Now you're set to start TDD-ing! When you've written your first test, you can run the tests in watch mode by running yarn test:watch

Instructions:

1. Model a Rectangle

create a file named Rectangle.js
in it, create a class named Rectangle, with the following properties in the constructor:
- breadth
- length
define a method named area() to return the area of the circle
- formula: area = length * breadth
instantiate the following rectangles one by one and verify that area() returns the expected values as stated below

breadth	length	area()	perimeter()
2	4	8	12
5	10	50	30

Repeat these steps for perimeter()

formula: perimeter = 2 * length + 2 * breadth

2. Model a Circle

create a file named Circle.js
in it, create a class named Circle, with the following property in the constructor:
- radius
define a method named area() to return the area of the circle
- formula: area = Math.PI * r ** 2
- hint: look up the javascript Math object docs to find out how to round a number to 1 decimal place (MDN calls this a 'single precision float')
instantiate the following circles one by one and verify that area() returns the expected values as stated below

radius	area()	perimeter()
1	3.14	6.3
2	12.6	12.6
3	28.3	18.9

Repeat these steps for perimeter()

formula: perimeter = 2 * Math.PI * r

3. Bonus: Model a SimpleCalculator

For this bonus exercise, don't use assertEquals. Instead, console.log to see the output of your methods and manually check whether it matches your expected values
create a file named SimpleCalculator
in it, create a class named SimpleCalculator, with the following property in the constructor:
- value (this will be the starting value). If no argument is supplied during instantiation, value should default to 0
Implement (i.e. write code for) the following methods.
- calculator.add(n)
- calculator.subtract(n)
- calculator.multiply(n)
- calculator.divide(n)
Implementation logic for each method:
- take in one argument (n)
- use n to update the value of this.value
- return this so that we can chain methods (example: calculator.add(12).multiply(2).divide(2))

AlnurFaisal / javascript-classes