in packages/fbjs/src/unicode/UnicodeHangulKorean.js [137:152]
function toConjoiningJamo(string) {
if (!hasCompatibilityOrSyllable(string)) {
return string;
}
const result = [];
for (let i = 0; i < string.length; i++) {
const charStr = string.charAt(i);
const codeUnit = charStr.charCodeAt(0);
result.push(
(CBASE <= codeUnit && codeUnit < CTOP) ? fromCompatibility(codeUnit) :
(SBASE <= codeUnit && codeUnit < STOP) ? decomposeSyllable(codeUnit) :
charStr);
}
return result.join('');
}