Chrome Extension Chrome Console

(Before reading this, know that I am a beginning coder/developer just learning how to code JavaScript).

I have been learning JavaScript through learning about Chrome Extensions and stuff like that in my free time. I had an idea a while back to create a "Slacker Radio Next Song Extension". (Slacker Radio is like one of those radio website, similar to Pandora). I decided to create a Chrome Extension that would read the console commands that were inputed into it. I realized that it was impossible (or at least I think) to read the commands going into the chrome console. But I realized that the command that went through looked alot like HTML code, so I think I have gained a new hope for my extension. Because I might be able to do something like

var albumCoverLink = document.getElementsByClassName("albumCoverArt");
document.write(albumCoverLink);

to possibly assign these things to a variable (things as in links/song names)

Screenshot to view the code stuff. If you look at the included screenshot that I have added, you can see the different variables (I think?) like the "albumCoverArt", which is a link that leads you to the album cover art image. I am trying to have my JavaScript code in my Chrome extension to be able to read these variables and to assign any links or title to a variable and use it in my code. I want to use

var albumCoverLink = document.getElementsByClassName("albumCoverArt");
document.write(albumCoverLink);

But I cant quite seem to get it to work. I might be going down the complete wrong path for this, (If I am, tell me) but I would very much enjoy if I could get some help on this.