en.javascript.info/1-js/8-oop/2-internal-external-interface/1-add-method-property-coffeemachine/solution.md

Кофеварка с новым методом:

//+ run
function CoffeeMachine(power) {
  this.waterAmount = 0;

  var WATER_HEAT_CAPACITY = 4200;
*!*
  var timerId;
*/!*
  var self = this;

  function getBoilTime() {
    return self.waterAmount * WATER_HEAT_CAPACITY * 80 / power;
  }

  function onReady() {
    alert( 'Кофе готово!' );
  }

  this.run = function() {
*!*
    timerId = setTimeout(onReady, getBoilTime());
*/!*
  };

*!*
  this.stop = function() {
    clearTimeout(timerId)
  };
*/!*
}


var coffeeMachine = new CoffeeMachine(50000);
coffeeMachine.waterAmount = 200;

coffeeMachine.run();
coffeeMachine.stop(); // кофе приготовлен не будет