From fef2d408f6520aa4e7ed6647d1968bb42fc126c7 Mon Sep 17 00:00:00 2001 From: Robin Townsend Date: Thu, 5 Aug 2021 17:56:16 -0400 Subject: [PATCH] Add comments to isRegionalIndicator Signed-off-by: Robin Townsend --- src/emoji.ts | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/src/emoji.ts b/src/emoji.ts index e871e0bb58..ee84583fc9 100644 --- a/src/emoji.ts +++ b/src/emoji.ts @@ -35,8 +35,15 @@ export const EMOTICON_TO_EMOJI = new Map(); export const getEmojiFromUnicode = unicode => UNICODE_TO_EMOJI.get(stripVariation(unicode)); -const isRegionalIndicator = (x: string): boolean => - Array.from(x).length === 1 && x >= '\u{1f1e6}' && x <= '\u{1f1ff}'; +const isRegionalIndicator = (x: string): boolean => { + // First verify that the string is a single character. We use Array.from + // to make sure we count by characters, not UTF-8 code units. + return Array.from(x).length === 1 && + // Next verify that the character is within the code point range for + // regional indicators. + // http://unicode.org/charts/PDF/Unicode-6.0/U60-1F100.pdf + x >= '\u{1f1e6}' && x <= '\u{1f1ff}'; +}; const EMOJIBASE_GROUP_ID_TO_CATEGORY = [ "people", // smileys