javascript function returning an undefined object

Question

i saw this code online and this is its contents.

       var shoppingcart = (function ()  {

             var _calculatePrice = function() {
                 return this.price * this.amount;
          };
          return {
              calculatePrice : _calculatePrice
           }
        })();

        var goods = {
           name: 'hammer',
           price: 199,
           amount: 2
        }
        shoppingCart.calculatePrice.call(goods)

And this is where i am not comfortable. the function returning an undefined object in {calculatePrice : _calculatePrice}. how does that really work? i thought it will do no harm to return just _calculatePrice

Answer 1

Firstly Typo at line 1.: change shoppingcart to shoppingCart

 var shoppingCart = (function() { var _calculatePrice = function() { return this.price * this.amount; }; return { calculatePrice: _calculatePrice } })(); var goods = { name: 'hammer', price: 199, amount: 2 } console.log(shoppingCart.calculatePrice.call(goods))

Explanation:

The returned object is:

{
    calculatePrice: _calculatePrice
}

It's property calculatePrice is variable _calculatePrice .

_calculatePrice references a function that returns a calculated Number.

.call() function helps you call a function with reference at global scope. Thats why the calculation function uses this.price & this.amount .

Answer 2

There is a typo : you declare a var shoppingcart and then you call it shoppingCart with C instead of c.

try to change de var declaration to: var shoppingCart = ....