Easter egg: The example is named dogcow, after a 90s Mac icon, designed by Susan Kare, which later became a small mascot: https://512pixels.net/dogcow/
Regarding .length: Effectly that is just the result of Unicode, there is no one-to-one equivalent between characters code points, the code units in an encoding and the resulting grapheme clusters. That is in effect a result of the complexity of the world's alphabets, including Emoji.