Fluent Calculator [js]

FluentCalculator.js

var Magic = function() {
  var value = 0;
  
  var operators = {
    'plus': (a, b) => a + b,
    'minus': (a, b) => a - b,
    'times': (a, b) => a * b,
    'dividedBy': (a, b) => a / b
  };
  
  var numbers = [
    'zero', 'one', 'two', 'three', 'four', 'five',
    'six', 'seven', 'eight', 'nine', 'ten'
  ];
  
  Object.keys(operators).forEach((operator) => {
    var operatorFunction = operators[operator];
    var operatorObject = {};
    
    numbers.forEach((num, index) => {
      Object.defineProperty(operatorObject, num, {
        get: () => value = operatorFunction(value, index)
      });
    });
    
    Number.prototype[operator] = operatorObject;
  });
  
  numbers.forEach((num, index) => {
    Object.defineProperty(this, num, {
      get: () => {
        value = index;
        return Number(index);
      }
    });
  });
}

var FluentCalculator = new Magic();
console.log(FluentCalculator.two.plus.three); // 5