This is fun and informative. Great job! Many of these JS gotchas you usually don't find out unless you're either writing library code or you're really unlucky.

This is fun and informative. Great job! Many of these JS gotchas you usually don't find out unless you're either writing library code or you're really unlucky. For example, I'd say it's pretty weird for someone to create an script element and not attach it to the DOM at the same time.