ASP.Net Core MVC: Check Username Availability (Exists) in Database using jQuery AJAX

Here Mudassar Khan has explained with an example, how to check Username availability i.e. check whether Username exists in database or not using jQuery AJAX and Entity Framework in ASP.Net Core MVC. This article will illustrate how to check Username availability in database on Registration Form by making AJAX call to database using jQuery AJAX and Entity Framework in ASP.Net Core MVC.