/* Get Programming with JavaScript

 * Listing 4.12

 * Using functions to add and display tax

 */

​

var sale1;

var sale2;

var sale3;

var sale;

var calculateTax;

var displaySale;

​

sale1 = { price: 140, taxRate: 15 };

sale2 = { price: 40, taxRate: 10 };

sale3 = { price: 120, taxRate: 20 };

​

calculateTax = function () {

    sale.tax = sale.price * sale.taxRate / 100;

    sale.total = sale.price + sale.tax;

};

​

displaySale = function () { 

  console.log("price = $" + sale.price);

  console.log("tax @ " + sale.taxRate + "% = $" + sale.tax);

  console.log("total cost = $" + sale.total);

};

​

sale = sale1;

calculateTax();

displaySale();

​

sale = sale2;

calculateTax();

displaySale();

​

sale = sale3;

calculateTax();

displaySale();

​

​

​

/* Further Adventures

 *

 * 1) Add a fourth sale object.

 *

 * 2) Update the code so that tax is calculated

 *    and the new sale is displayed.

 *

 * Having two separate functions to calculate tax

 * and display sales is good, each has a specific purpose.

 * Having to call both functions

 * for each sale object is not so good.

 *

 * 3) Can you change the code so that you don't

 *    have to call both functions for every sale?

 *

 */