This includes code to swap or modify gender, and adjust the skin tone of emoji.
There's also some browser-only code to guess whether an emoji is supported on your user's platform.
It's browser-only as it requires
Every emoji release add a number of new basic emoji. However, many releases have tweaked or update the rules for emoji, typically w.r.t. combined emoji and gender.
Emoji 12.1 added nearly all missing gender neutral professions. Previously, professions were only created by "MAN/WOMAN + ZWJ + ROLE", e.g. "MAN + ZWJ + MICROPHONE" for "MAN SINGER", but 12.1 allows "PERSON + ZWJ + ROLE".
Additionally, across 12.0 and 12.1, support was added for skin tones for the "WOMAN AND MAN HOLDING HANDS" and related emoji. This allows different skin tones for both people in the emoji.
Emoji 13 made minor but interesting changes:
Added a gender neutral "MX CLAUS" to go with "SANTA CLAUS" and "MRS CLAUS". This gender neutral version is made up of "PERSON + ZWJ + HOLIDAY TREE", but the gendered versions still have a single old-style code point each. (ok-emoji can expando this to the "MAN/WOMAN + ZWJ + HOLIDAY TREE" for manipulation.)
It repurposed two old gendered emoji to create neutral "PERSON IN TUXEDO" and "PERSON IN VEIL", with new role variants ("MALE/FEMALE" roles).