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How to count the correct length of a string with emojis in javascript?

I’ve a little problem.

I’m using NodeJS as backend. Now, an user has a field “biography”, where the user can write something about himself.

Suppose that this field has 220 maxlength, and suppose this as input:

šŸ‘¶šŸ»šŸ‘¦šŸ»šŸ‘§šŸ»šŸ‘ØšŸ»šŸ‘©šŸ»šŸ‘±šŸ»ā€ā™€ļøšŸ‘±šŸ»šŸ‘“šŸ»šŸ‘µšŸ»šŸ‘²šŸ»šŸ‘³šŸ»ā€ā™€ļøšŸ‘³šŸ»šŸ‘®šŸ»ā€ā™€ļøšŸ‘®šŸ»šŸ‘·šŸ»ā€ā™€ļøšŸ‘·šŸ»šŸ’‚šŸ»ā€ā™€ļøšŸ’‚šŸ»šŸ•µšŸ»ā€ā™€ļøšŸ‘©šŸ»ā€āš•ļøšŸ‘ØšŸ»ā€āš•ļøšŸ‘©šŸ»ā€šŸŒ¾šŸ‘ØšŸ»ā€šŸŒ¾šŸ‘ØšŸ»ā€šŸŒ¾šŸ‘ØšŸ»ā€šŸŒ¾šŸ‘ØšŸ»ā€šŸŒ¾šŸ‘ØšŸ»ā€šŸŒ¾šŸ‘ØšŸ»ā€šŸŒ¾šŸ‘ØšŸ»ā€šŸŒ¾šŸ‘ØšŸ»ā€šŸŒ¾šŸ‘ØšŸ»ā€šŸŒ¾šŸ‘ØšŸ»ā€šŸŒ¾šŸ‘ØšŸ»ā€šŸŒ¾šŸ‘ØšŸ»ā€šŸŒ¾šŸ‘ØšŸ»ā€šŸŒ¾šŸ‘ØšŸ»ā€šŸŒ¾šŸ‘ØšŸ»ā€šŸŒ¾ 

As you can see there aren’t 220 emojis (there are 37 emojis), but if I do in my nodejs server

console.log(bio.length)

where bio is the input text, I got 221. How could I “parse” the string input to get the correct length? Is it a problem about unicode?

SOLVED

I used this library: https://github.com/orling/grapheme-splitter

I tried that:

var Grapheme = require('grapheme-splitter');
var splitter = new Grapheme();
console.log(splitter.splitGraphemes(bio).length);

and the length is 37. It works very well!

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Answer

  1. str.length gives the count of UTF-16 units.

  2. Unicode-proof way to get string length in codepoints (in characters) is [...str].length as iterable protocol splits the string to codepoints.

  3. If we need the length in graphemes (grapheme clusters), we have these native ways:

    a. Unicode property escapes in RegExp. See for example: Unicode-aware version of w or Matching emoji.

    b. Intl.Segmenter — coming soon, probably in ES2021. Can be tested with a flag in the last V8 versions (realization was synced with the last spec in V8 86). Unflagged (shipped) in V8 87.

See also:

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