can you use jquery to target div in a flexbox markup if it is offline

can you use jquery to target div in a flexbox markup if it is offline

I am attempting to change several off line framework based educational "apps" (study-ssytems ????) to flexbox before frames go away.

It seems the only way to target a div is thru javascript or Jquery.  I know neither.  Ouch!  I am a teacher who never took a computer course.  But have developed with raw css1 til now 3 and html 2 til now changing to 5 educational "apps"  they are note taking systems and study resources.  It's not small as I have more than 10,000 links. in the 86gb  of files. 

Everything works in frames.  But I see its time to change.

Is it possible to do this with Jquery - off line.  If so where does an absolute beginner begin with such a big project?

I saw something JakeClgar wrote

How to follow a hyperlink in a div, and have page show in same div?

by Roger Wilkinson last modified on 21-Jan Forum
But I am not sure this is an answer.  Plus I have more than 10,000 links