Can you copy the client side Javascript code of a site?

I think you can copy the html/css of a site, can you do the same with javascript? basically can you copy the entire frontend of a site along with the content etc and create your own site with it?

Lastly, can you copy the code and load it to wordpress or a theme somehow without having knowledge about wordpress and php?

1. Yes
2. No

Front-end javascript (DOM Modification elements etc.) - yes.

You'll require a working knowledge of javascript to be able to use a piece of code on a different website.

You can lookup all the client-side javascript of a server you want, just look at the html and you will probably most of it. But taking html,css,js into wordpress I don't think will work honestly, or at least not that easy probably you have some sort of plugins.

Oh I just noticed that there are other languages too within html when you view the code of a page, is it possible to copy only the html/css part? or do I have to slice the entire page through photoshop? (if possible)

Also, Can I load html/css to a wordpress theme in order to customize the appearance but still being able to use plugins etc? those are markup languages so I'm not sure if they work the same like javascript. Also If that's possible, can I edit the copied elements as drafts instead of code?

OP it might be easier to explain what you are trying to do.

Code works on client side (browser - JavaScript) and server side (server - php).

If you want to clone a site, there are tools to do that (mostly hit or miss), if you want to copy the style of a site then just use a similar Wordpress theme or hire a web dev.

If you know code then you can do it yourself but clearly you don't and it would be hard for you to understand what to do if it was explained to you.
Although there are tutorials on the web/YouTube.

Yea is possible but javascript is not as easy as you may think especially if the code was not written nor plan by you.