Moving the Shopping Cart Module

I want to do one last thing. The shopping cart controller is mighty handy. No doubt we want to reuse this functionality in Node.js to create invoices. Luckily, we have kind of future proofed our frontend scripts with Browserify already, so we can simply create a module and use it on both the frontend and backend.

Create a new file in your scripts folder and name it order.js. In it goes most of the code from the shopping-cart.js file:

module.exports = (function () {
   var Order = function () {
      this.lines = [];
   };

   Order.prototype.removeLine = function (line) {
      this.lines.splice(this.lines.indexOf(line), 1);
   };

   [...]

   return {
      Order: Order,
      Line: Line
   };
})();

Since we are not working on the $scope object anymore, we need some new object to contain the Line objects. So, we create an Order constructor that has a lines array. The total function and the removeLine function are put on Order prototype. Please note that removeLine...