How does facebook detect when a link as been PASTED

Question

Facebook\'s status update input (well, contenteditable div) detects links.

When typing a link it waits until the spacebar is pressed before fetching the URL.

Answer 1

I am actually going to suggest it listens to every keyup because it has multiple uses, if you type @ it will suggest friends, etc.

It probably scans the text and finds links and makes them, well linkable, and then crawls the page so you can post it as "Sharing" the page.