KnockoutJS Essentials

Extending the customer model

You also need to validate the customer data. These are the rules for validation:

• A first name is required
• A last name is required and it needs a minimum of three characters
• An address is required and it needs a minimum of five characters
• An e-mail address is required and must match the built-in e-mail pattern
• The zip code is required and must contain five numbers

To achieve this task, make some updates in the code, as follows:

1. Extend the customer object in the models/Customer.js file:

   var firstName = ko.observable('').extend({
     required: true
   });
   var lastName = ko.observable('').extend({
     required: true,
     minLength: 3
   }); var fullName = ko.computed(function(){ return firstName() + ' ' + lastName(); }); var address = ko.observable(''). ...