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Emoji Patterns

Description

This Node module returns a JSON-compatible object literal containing both basic and compound emoji pattern strings.

Available Patterns

The following patterns are generated using the information parsed from the Emoji 14.0 data files emoji-data.txt, emoji-sequences.txt and emoji-zwj-sequences.txt:

• Basic_Emoji
• Emoji
• Emoji_Component
• Emoji_Keycap_Sequence
• Emoji_Modifier
• Emoji_Modifier_Base
• Emoji_Presentation
• Extended_Pictographic
• RGI_Emoji_Flag_Sequence
• RGI_Emoji_Modifier_Sequence
• RGI_Emoji_Tag_Sequence
• RGI_Emoji_ZWJ_Sequence

These basic patterns are then used to generate two more complex compound patterns:

• Emoji_All
• Emoji_Keyboard

const
{
    Basic_Emoji,
    Emoji,
    Emoji_Component,
    Emoji_Keycap_Sequence,
    Emoji_Modifier,
    Emoji_Modifier_Base,
    Emoji_Presentation,
    Extended_Pictographic,
    RGI_Emoji_Flag_Sequence,
    RGI_Emoji_Modifier_Sequence,
    RGI_Emoji_Tag_Sequence,
    RGI_Emoji_ZWJ_Sequence
} = emojiPatterns;

// Keyboard emoji only (fully-qualified and components)
emojiPatterns["Emoji_Keyboard"] = `(?:${RGI_Emoji_ZWJ_Sequence}|${Emoji_Keycap_Sequence}|${RGI_Emoji_Flag_Sequence}|${RGI_Emoji_Tag_Sequence}|${Emoji_Modifier_Base}${Emoji_Modifier}|${Emoji_Presentation}|${Emoji}\\uFE0F)`;
// All emoji (U+FE0F optional)
emojiPatterns["Emoji_All"] = emojiPatterns["Emoji_Keyboard"].replace (/(\\u{FE0F}|\\uFE0F)/gi, '$1?');

Notes

• The order of the basic patterns in the compound patterns is critical. Since a regular expression engine is eager and stops searching as soon as it finds a valid match (i.e., it always returns the leftmost match), the longest patterns must come first. The same strategy is also used when generating the RGI_Emoji_ZWJ_Sequence pattern itself.

• In the compound patterns, ${Emoji_Modifier_Base}${Emoji_Modifier} can be replaced by ${RGI_Emoji_Modifier_Sequence} which is strictly equivalent (but more verbose).

• Likewise, ${Emoji_Presentation}|${Emoji}\\uFE0F could be replaced by ${Basic_Emoji} (which should actually be called ${Basic_Emoji_Sequence} for the sake of consistency), but the latter is more restrictive since it only contains the 5 skin tone and 4 hairstyle components, excluding the 12 keycap bases and the 26 singleton regional indicators.

• Providing patterns as strings instead of regular expressions does require the extra step of using new RegExp () to actually make use of them, but it has two main advantages:

  • Flags can be set differently depending on how the patterns are used.

  • The patterns can be further modified before being turned into regular expressions; for instance, unwanted sub-patterns can be discarded by replacing them with an empty string, or the pattern can be embedded into a larger one. See examples below.

Installing

Switch to your project directory (cd) then run:

npm install emoji-patterns

Testing

A basic test can be performed by running the following command line from the package directory:

npm test

Examples

Testing whether an emoji has a keyboard status or not

const emojiPatterns = require ('emoji-patterns');
const emojiKeyboardRegex = new RegExp ('^' + emojiPatterns["Emoji_Keyboard"] + '$', 'u');
console.log (emojiKeyboardRegex.test ("❤️"));
// -> true
console.log (emojiKeyboardRegex.test ("❤"));
// -> false

Extracting all emoji from a string

const emojiPatterns = require ('emoji-patterns');
const emojiAllRegex = new RegExp (emojiPatterns["Emoji_All"], 'gu');
console.log (JSON.stringify ("AaĀā#*0❤🇦愛爱❤️애💜".match (emojiAllRegex)));
// -> ["#","*","0","❤","🇦","❤️","💜"]

Extracting all emoji from a string, except keycap bases and singleton regional indicators

const emojiPatterns = require ('emoji-patterns');
const emojiAllPattern = emojiPatterns["Emoji_All"];
const customPattern = emojiAllPattern.replace (/\\u0023\\u002A\\u0030-\\u0039|\\u\{1F1E6\}-\\u\{1F1FF\}/gi, '');
const customRegex = new RegExp (customPattern, 'gu');
console.log (JSON.stringify ("AaĀā#*0❤🇦愛爱❤️애💜".match (customRegex)));
// -> ["❤","❤️","💜"]

Extracting all keyboard-status emoji from a string

const emojiPatterns = require ('emoji-patterns');
const emojiAllRegex = new RegExp (emojiPatterns["Emoji_All"], 'gu');
const emojiKeyboardRegex = new RegExp ('^' + emojiPatterns["Emoji_Keyboard"] + '$', 'u');
let emojiList = "AaĀā#*0❤🇦愛爱❤️애💜".match (emojiAllRegex);
if (emojiList)
{
    emojiList = emojiList.filter (emoji => emojiKeyboardRegex.test (emoji));
}
console.log (JSON.stringify (emojiList));
// -> ["🇦","❤️","💜"]

Removing all emoji from a string

const emojiPatterns = require ('emoji-patterns');
const emojiAllRegex = new RegExp (emojiPatterns["Emoji_All"], 'gu');
console.log (JSON.stringify ("AaĀā#*0❤🇦愛爱❤️애💜".replace (emojiAllRegex, "")));
// -> "AaĀā愛爱애"

Caveats

• The basic patterns strictly follow the information extracted from the data files. Therefore, the following characters are considered Emoji in the emoji-data.txt file, although they are omitted in the emoji-test.txt file, as well as in the CLDR annotation files provided in XML format:

  • 12 keycap bases: number sign '#', asterisk '*', digits '0' to '9'
  • 26 singleton regional indicators: '🇦' to '🇿'

• The regular expressions must include a 'u' flag, since the patterns make use of the new type of Unicode escape sequences: \u{1F4A9}.

• The two main regular expression patterns Emoji_All and Emoji_Keyboard are pretty big, around 65KB each...

License

The MIT License (MIT).

Copyright © 2018-2021 Michel MARIANI.