I’m trying ….I had an idea so

Ok so here is what I want to do….

I want to write a script that compares an html element from a external website with an element located on my local file.

For example I go to stackoverflow.com and
run the webprogram(scripts) to compare x element with my z element located on my local file. Let’s make clear that I don’t want to save any information from stackoverflow I just want to compare the elements.

Is this possible with Javascript or I’m just to stupid?

Total newbie Ofc……