Checking if a username already exists asynchronously - ASP.NET

Question

I have seen several websites nowadays that asynchronoulsy checks if the user name you are typing is available or not. It appears that they use AJAX for this (and capture the textbox on changed event and maybe call a server side method that does a DB call?)

For a ASP.NET/C# site, how would I go about doing this? I would really appreciate specific answers (and hopefully point me to an open source code that I could use to analyze the architecture of a website that does stuff like this?)

Answer 1

Steps:

1. Create a simple service to check availability of a username.

2. Wire javascript to call the service when the text in the textbox on your page has changed.

3. Call your simple service with the text in the textbox.

4. Parse the result of your service call and render the alert on the page.