Fallback for CDN ?

Answer 1

really hard to understand what you want from such a question with no content....
i assume you mean something like this...?
http://fallback.io
or this if you do not want to rely on another library (i assume the same principle in the example can be used for other loaded scripts)
https://css-tricks.com/snippets/jquery/fallback-for-cdn-hosted-jquery/

Answer 2

thanks ,this is what i need