A JavaScript implementation of the Unicode grapheme cluster breaking algorithm (UAX #29)
It is important to recognize that what the user thinks of as a “character”—a basic unit of a writing system for a language—may not be just a single Unicode code point. Instead, that basic unit may be made up of multiple Unicode code points. To avoid ambiguity with the computer use of the term character, this is called a user-perceived character. For example, “G” + acute-accent is a user-perceived character: users think of it as a single character, yet is actually represented by two Unicode code points. These user-perceived characters are approximated by what is called a grapheme cluster, which can be determined programmatically.
You can install via npm
npm install grapheme-breaker
var GraphemeBreaker = require('grapheme-breaker');
// break a string into an array of grapheme clusters
GraphemeBreaker.break('Z͑ͫ̓ͪ̂ͫ̽͏̴̙̤̞͉͚̯̞̠͍A̴̵̜̰͔ͫ͗͢L̠ͨͧͩ͘G̴̻͈͍͔̹̑͗̎̅͛́Ǫ̵̹̻̝̳͂̌̌͘!͖̬̰̙̗̿̋ͥͥ̂ͣ̐́́͜͞') // => ['Z͑ͫ̓ͪ̂ͫ̽͏̴̙̤̞͉͚̯̞̠͍', 'A̴̵̜̰͔ͫ͗͢', 'L̠ͨͧͩ͘', 'G̴̻͈͍͔̹̑͗̎̅͛́', 'Ǫ̵̹̻̝̳͂̌̌͘', '!͖̬̰̙̗̿̋ͥͥ̂ͣ̐́́͜͞']
// or just count the number of grapheme clusters in a string
GraphemeBreaker.countBreaks('Z͑ͫ̓ͪ̂ͫ̽͏̴̙̤̞͉͚̯̞̠͍A̴̵̜̰͔ͫ͗͢L̠ͨͧͩ͘G̴̻͈͍͔̹̑͗̎̅͛́Ǫ̵̹̻̝̳͂̌̌͘!͖̬̰̙̗̿̋ͥͥ̂ͣ̐́́͜͞') // => 6
// use nextBreak and previousBreak to get break points starting
// from anywhere in the string
GraphemeBreaker.nextBreak('😜🇺🇸👍', 3) // => 6
GraphemeBreaker.previousBreak('😜🇺🇸👍', 3) // => 2In order to use the library, you shouldn't need to know this, but if you're interested in contributing or fixing bugs, these things might be of interest.
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The
src/classes.coffeefile is automatically generated fromGraphemeBreakProperty.txtin the Unicode database bysrc/generate_data.coffee. It should be rare that you need to run this, but you may if, for instance, you want to change the Unicode version. -
You can run the tests using
npm test. They are written usingmocha, and generated fromGraphemeBreakTest.txtandemoji-test.txtfrom the Unicode database, which is included in the repository for performance reasons while running them.
MIT