Some sites don't have everything in the page source code, you can only see the new elements when you load the page on a browser. I don't know why is that, I'm thinking maybe it's because a site requires javascript to be enabled? In python, I fixed my issue with the "AsyncHTMLSession" module and this code:
r = await session.get(url)
await r.html.arender()
It let me grab the new elements and do whatever I needed, is there anything like this for node.js?
Yes, basically you are looking for a way to access content that shows up when a page loads using JavaScript.
The solution you want is a headless browser - puppeteer does this very well.
Checkout: https://www.toptal.com/puppeteer/headless-browser-puppeteer-tutorial
Or even a quick video: https://www.youtube.com/watch?v=dXjKh66BR2U