in src/behaviors/emoji/support/is_emoji_unicode_supported.js [13:21]
function isRainbowFlagEmoji(emojiUnicode) {
const characters = Array.from(emojiUnicode);
// Length 4 because flags are made of 2 characters which are surrogate pairs
return (
emojiUnicode.length === 4 &&
characters[0].codePointAt(0) === baseFlagCodePoint &&
characters[1].codePointAt(0) === rainbowCodePoint
);
}