Functional Programming in JavaScript - 8

gistfile1.js

const CIRCLE = "circle";
const SQUARE = "square";
const RECTANGLE = "rectangle";

var getAreaFunction = function (shape) {
  return function () {
    switch (shape) {
      case CIRCLE:
        return Math.PI * arguments[0] * arguments[0];
        break;
      case SQUARE:
        return arguments[0] * arguments[0];
        break;
      case RECTANGLE:
        return arguments[0] * arguments[1];
        break;
    }
  };
};

var Shape = function (type) {
  var area = getAreaFunction(type);
  return {
    getArea:function () {
      return Math.round(Number(area.apply(this, arguments)));
    }
  };
};

var aCircle = new Shape(CIRCLE);
var aSquare = new Shape(SQUARE);
var aRectangle = new Shape(RECTANGLE);

console.log(aCircle.getArea(50));
console.log(aSquare.getArea(50));
console.log(aRectangle.getArea(50, 20));