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:
Extend the customer object in the
models/Customer.jsfile: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('').extend({ required: true, minLength: 5 }); var email = ko.observable('').extend({ required: true, email: true }); var zipCode = ko.observable('').extend({ required: true, pattern: { message: 'Zip code should have 5 numbers...