I want to learn JS and now that I have a specific purpose in mind it seems like it might be a good opportunity to start?
Here's what I'm looking to accomplish:

1. The script would apply to/run on this page only: https://9gans.com/
2. For each of the 9 images appearing in the grid, a button will appear beneath it
3. Clicking an image's button saves that image however the saved image should be the hi-res version, which is achieved by replacing mini with originals in the image URL
4. Default download dir is fine and filename should be 9G-yyyyMMdd-HHmmss.jpg

First: can I do all of this with JS?
Second: where should I begin? can you give me some keywords that I can search for that will help me piece this all together?
Third: thanks for reading! I hope for some replies