To show proper alerts or notifications to a user is a part of interactive web application. There are many library to fulfill this requirement but messenger.js is very handy, advanced and useful for this purpose.
With the help of messenger.js you can show beautiful alerts or notifications in your web applications. The alerts or notifications can be shown in top, bottom or either corner of the web page. The library comes as jquery plugin and also works with ajax based functions. You can wrap AJAX requests with progress, success and error messages.
The plugin also support theming and comes with some default themes. The look and feel of the alerts can be changed easily.