JS: String.fromCharCode (Char ID to Char) ❌

• 🟢 TIP: better is String.fromCodePoint

String.fromCharCode(char_id_1, char_id_2, etc)

Turn each Char ID into a character and join them, return a string. char_id is a integer.

• Unicode: Code Point (Char ID)

🛑 WARNING: does not work if char_id is greater than 65535. If it is greater than 65535, a value of modulo(char_id, 2^16) is used.

🛑 WARNING: string methods do not work the way you think if it contains characters outside of Unicode Basic Multilingual Plane (e.g. emoji 🦋.). See JS: String Index Code Unit

/*
convert sequence of unicode codepoint to string.
97 is the codepoint for letter a.
98 is the codepoint for letter b.
*/
console.log(String.fromCharCode(97, 98));
// ab

// String.fromCharCode() does not work for emoji or other rare unicode char

// try to generate the butterfly 🦋 char
console.log(String.fromCharCode(129419));
// 曆

// result is not what we want

/*
🦋
Name: BUTTERFLY
ID 129419
HEXD 1F98B
UTF8  F0 9F A6 8B
UTF16 D83E DD8B
*/