Handle Unicode text, emoji, encoding, normalization, code points, and safe storage.
Lessons
Read and build characters by code point.
codePointAt & fromCodePoint is easiest to learn by reading the example, changing it, and observing the result.
const text = 'a😀b';
console.log(text.length); // 4 (UTF-16 code units)
console.log([...text].length); // 3 (code points)
console.log(text.codePointAt(1).toString(16)); // 1f600
console.log(String.fromCodePoint(0x1F600)); // 😀Practice the codePointAt & fromCodePoint example in a small scratch file, then explain what changed and why.