KnockoutJS by Example

Handling the authentication error

This user story is about displaying a message to the user if the login fails based on the username and password that the user has provided. To implement this user story, we will take the following steps:

• Add a flag to the authenticator module to show or hide the authentication error
• Modify the login method of the authenticator module to check for the authentication error
• Update the view to add an alert box with the authentication error

Let's get started by opening the authenticator module and adding an observable that will serve as a flag to show or hide the authentication error alert box:

/* flag to show authentication failed message */
var showAuthenticationFailed = ko.observable(false);

Add the preceding flag to ...