How To Filter A Page Using Javascript ?

Let's say I want to filter the contents of a target web page, and
present a simpler page on the screen.

For example, let's say a target web page is full of links, text, images,
forms, etc. and I want to present a simple page containing just the links.

The original page is not "mine", that is, I can't just edit it in
notepad and stick some javascript in it.

So, what I want to do is write some javascript on a new page that I'm
developing, that will somehow "access" or "read" the target page, scan
and find all the links, and present them to the user.

My question is, what's a straightforward way from javascript to access
the target page ?

Should I be somehow loading it into a DOM object and then "walking" the
tree ?

Or should I somehow read it's HTML as text strings and parse it looking
for anchor links ?

What functions, methods, classes, objects in javascript achieve the goal
of something accessing a remote page and "looking" at its contents.