@naytev/grapheme-splitter

    1.0.0 • Public • Published

    Background

    In JavaScript there is not always a one-to-one relationship between string characters and what a user would call a separate visual "letter". Some symbols are represented by several characters. This can cause issues when splitting strings and inadvertently cutting a multi-char letter in half, or when you need the actual number of letters in a string.

    For example, emoji characters like "🌷","🎁","💩","😜" and "👍" are represented by two JavaScript characters each (high surrogate and low surrogate). That is,

    "🌷".length == 2

    What's more, some languages often include combining marks - characters that are used to modify the letters before them. Common examples are the German letter ü and the Spanish letter ñ. Sometimes they can be represented alternatively both as a single character and as a letter + combining mark, with both forms equally valid:

    var two = ""; // unnormalized two-char n+◌̃  , i.e. "\u006E\u0303";
    var one = "ñ"; // normalized single-char, i.e. "\u00F1"
    console.log(one!=two); // prints 'true'

    Unicode normalization, as performed by the popular punycode.js library or ECMAScript 6's String.normalize, can sometimes fix those differences and turn two-char sequences into single characters. But it is not enough in all cases. Some languages like Hindi make extensive use of combining marks on their letters, that have no dedicated single-codepoint Unicode sequences, due to the sheer number of possible combinations. For example, the Hindi word "अनुच्छेद" is comprised of 5 letters and 3 combining marks:

    अ + न + ु + च + ् + छ + े + द

    which is in fact just 5 user-perceived letters:

    अ + नु + च् + छे + द

    and which Unicode normalization would not combine properly. There are also the unusual letter+combining mark combinations which have no dedicated Unicode codepoint. The string Z͑ͫ̓ͪ̂ͫ̽͏̴̙̤̞͉͚̯̞̠͍A̴̵̜̰͔ͫ͗͢L̠ͨͧͩ͘G̴̻͈͍͔̹̑͗̎̅͛́Ǫ̵̹̻̝̳͂̌̌͘ obviously has 5 separate letters, but is in fact comprised of 58 JavaScript characters, most of which are combining marks.

    Enter the grapheme-splitter.js library. It can be used to properly split JavaScript strings into what a human user would call separate letters (or "extended grapheme clusters" in Unicode terminology), no matter what their internal representation is. It is an implementation of the Unicode UAX-29 standard.

    Installation

    To install grapheme-splitter to your project, use the NPM command below:

    $ npm install --save grapheme-splitter
    

    Tests

    To run the tests on grapheme-splitter, use the command below:

    $ npm test
    

    Usage

    Just initialize and use:

    var splitter = new GraphemeSplitter();
     
    // split the string to an array of grapheme clusters (one string each)
    var graphemes = splitter.splitGraphemes(string);
     
    // or do this if you just need their number
    var graphemeCount = splitter.countGraphemes(string);

    Examples

    var splitter = new GraphemeSplitter();
     
    // plain latin alphabet - nothing spectacular
    splitter.splitGraphemes("abcd"); // returns ["a", "b", "c", "d"]
     
    // two-char emojis and four-char country flag
    splitter.splitGraphemes("🌷🎁💩😜👍🇺🇸"); // returns ["🌷","🎁","💩","😜","👍","🇺🇸"]
     
    // diacritics as combining marks, 10 JavaScript chars
    splitter.splitGraphemes("Ĺo͂ře᷒m̅"); // returns ["Ĺ","o͂","ř","e᷒","m̅"]
     
    // individual Korean characters (Jamo), 4 JavaScript chars
    splitter.splitGraphemes("뎌쉐"); // returns ["뎌","쉐"]
     
    // Hindi text with combining marks, 8 JavaScript chars
    splitter.splitGraphemes("अनुच्छेद"); // returns ["अ","नु","च्","छे","द"]
     
    // demonic multiple combining marks, 75 JavaScript chars
    splitter.splitGraphemes("Z͑ͫ̓ͪ̂ͫ̽͏̴̙̤̞͉͚̯̞̠͍A̴̵̜̰͔ͫ͗͢L̠ͨͧͩ͘G̴̻͈͍͔̹̑͗̎̅͛́Ǫ̵̹̻̝̳͂̌̌͘!͖̬̰̙̗̿̋ͥͥ̂ͣ̐́́͜͞"); // returns ["Z͑ͫ̓ͪ̂ͫ̽͏̴̙̤̞͉͚̯̞̠͍","A̴̵̜̰͔ͫ͗͢","L̠ͨͧͩ͘","G̴̻͈͍͔̹̑͗̎̅͛́","Ǫ̵̹̻̝̳͂̌̌͘","!͖̬̰̙̗̿̋ͥͥ̂ͣ̐́́͜͞"]

    Acknowledgements

    This library is heavily influenced by Devon Govett's excellent grapheme-breaker CoffeeScript library at https://github.com/devongovett/grapheme-breaker with an emphasis on ease of integration and pure JavaScript implementation.

    Install

    npm i @naytev/grapheme-splitter

    DownloadsWeekly Downloads

    1,099

    Version

    1.0.0

    License

    MIT

    Last publish

    Collaborators

    • mbseid
    • mpierotti