Comunication with REST API services is essential in both front end and back end development. We'll have also to deal with asynchronous execution code.

Get familiar with the REST API Github. Learn how to retrieve information about a user. Also you should have some knowledge about how to execute AJAX calls and JSON notation.

1. Execute and explore the fetch_example folder
2. Implement the main exercise in both index.html and fetch.js files
3. The user should be able to write a Github username in the input field
   1. The form should validate that the input field value is not empty and only contains characters or numbers
   2. When the user clicks in "Search" button, an AJAX call should be performed to the GitHub API to retrieve information about the filled username
   3. A new row should be added in the table to display the avatar, bio, and the homepage of the given user.

Working DEMO

1. If the user does not exists in the GitHub database, an error message should be dislayed in the application; and no row should be added in the table.
2. If the username has an invalid Github username format, a different error should be display; and the application should immediatly terminate.