Object-Oriented Programming/Inheritance/JavaScript
index.js
edit// This program demonstrates use of the Polygon, Triangle, Rectangle, and Square classes.
const Polygon = require("./polygon");
const Square = require("./square");
const Rectangle = require("./rectangle");
const Triangle = require("./triangle");
main();
function main() {
let triangle = new Polygon([3, 4, 5]);
console.log("triangle sides:", triangle.sides);
console.log("triangle perimeter:", triangle.perimeter);
let rectangle = new Polygon([4, 2, 4, 2]);
console.log("rectangle sides:", rectangle.sides);
console.log("rectangle perimeter:", rectangle.perimeter);
let square = new Polygon([2, 2, 2, 2]);
console.log("square sides:", square.sides);
console.log("square perimeter:", square.perimeter);
triangle = new Triangle([3, 4, 5]);
console.log("triangle sides:", triangle.sides);
console.log("triangle perimeter:", triangle.perimeter);
console.log("triangle area:", triangle.area);
rectangle = new Rectangle([4, 2, 4, 2]);
console.log("rectangle sides:", rectangle.sides);
console.log("rectangle perimeter:", rectangle.perimeter);
console.log("rectangle area:", rectangle.area);
square = new Square([2, 2, 2, 2]);
console.log("square sides:", square.sides);
console.log("square perimeter:", square.perimeter);
console.log("square area:", square.area);
}
polygon.js
edit// Supports polygon calculations for perimeter.
class Polygon {
_sides = undefined;
// Creates a polygon object.
constructor(sides) {
this.sides = sides;
}
get perimeter() {
return this.sides.reduce((a, b) => a + b, 0);
}
}
module.exports = Polygon;
rectangle.js
edit// Supports rectangle calculations for perimeter and area.
const Polygon = require("./polygon");
class Rectangle extends Polygon {
// Creates a rectangle object.
constructor(sides) {
super(sides);
}
// Gets area of the rectangle.
get area() {
let length = this.sides[0];
let width = this.sides[1];
if (length == width) {
width = this.sides[2];
}
let area = length * width;
return area;
}
}
module.exports = Rectangle;
square.js
edit// Supports square calculations for perimeter and area.
const Polygon = require("./polygon");
class Square extends Polygon {
// Creates a square object.
constructor(sides) {
super(sides);
}
// Gets area of the square.
get area() {
let side = this.sides[0];
let area = side * side
return area;
}
}
module.exports = Square;
triangle.js
edit// Supports triangle calculations for perimeter and area.
const Polygon = require("./polygon");
class Triangle extends Polygon {
// Creates a triangle object.
constructor(sides) {
super(sides);
}
// Gets area of the triangle.
// References:
// https://www.mathsisfun.com/geometry/herons-formula.html
get area() {
let s = this.perimeter / 2;
let a = this.sides[0];
let b = this.sides[1];
let c = this.sides[2];
let area = Math.sqrt(s * (s - a) * (s - b) * (s - c));
return area;
}
}
module.exports = Triangle;
Try It
editCopy and paste the code above into one of the following free online development environments or use your own JavaScript compiler / interpreter / IDE.