Youtube.com built with?

Question

Recently Youtube gives me an option to change its theme. Actually i think youtube launches new theme. I was checking its code (Front end). It looks like angular, but i am not sure its angular or something else.

Is this angular code ? if yes then what version it is?

or

its something else?

Thank you for your attention. :)

Answer 1

They definitely don't use Angular.

They use a custom js "framework", and for navigation and dynamic updates they use something called SPF (Structured Page Fragments):

http://youtube.github.io/spfjs/