I have lots of ASP.NET Pages and server database connection.They takes some time to load fully when requested from server to client. Now I want to show a angular-loading-bar
I am not sure if I understand your question 100%. Can't you just overlay a div (may be gray - to show it's disable), and display the loading bar/gif?
Overlaying a div would be quite simple and you can find many resources like, How to overlay one div over another div overlay a div over another one with css