I learned that not every property key that looks the same is the same.
I learned how 'String.prototype.normalize' can improve daily string comparisons.
I learned that the Unicode character U+202E is perfect to trick your coworkers and turn everything around.
Have you ever thought about how Emoji work behind the scenes? I looked into this topic, and I pretty much felt like Alice in Wonderland: there's so much I didn't know about it!