Given a language, how to get its alphabet letters

Question

Is there a programmatic way (or some open-source repository), that given a language (say in 2-leters ISO format), return the letters of the alphabet of that language?

For example:

console.log(getAlphabet('en'));

outputs:

a b c d ... 

and

console.log(getAlphabet('he'));

outputs:

א ב ג ד ... 

• Mister Jojo: and for languages without alphabets?
• Tolgahan Dayanikli: I think that there is no pre-built library that has this feature.
• Thomas: Although following question was asked for Python, it may help you: stackoverflow.com/q/61182560/42659
• some: Are you going to support diacritics? AÁÀÂÄÃEÉÈÊËeéèêë?

Answer 1

I don't think that a language always has a well-defined alphabet associated with it. But in the Unicode CLDR standard, the //ldml/characters/exemplarCharacters seem to contain a "representative section" of letters typically used in a given language. This comes in an open-source repository, see here for Hebrew, for example.

Using an XML parser library, you can write a function that loads the file based on the language code (in the example above, https://raw.githubusercontent.com/unicode-org/cldr/HEAD/common/main/he.xml for language code he) and locates the //ldml/characters/exemplarCharacters element in it.

Below is an example function in client-side Javascript. It uses a regular expression with Unicode flag to split the exemplarCharacters into individual letters, even if they are represented by more than one Javascript character.

fetch("https://raw.githubusercontent.com/unicode-org/cldr/HEAD/common/main/he.xml")
 .then(r => r.text())
 .then(function(xml) {
 var dom = new DOMParser().parseFromString(xml, "text/xml");
 console.log(dom.evaluate("/ldml/characters/exemplarCharacters[1]", dom, undefined, XPathResult.STRING_TYPE).stringValue
 .match(/[^ \[\]]/gu));
 });

Alternatively, you could evaluate /ldml/characters/exemplarCharacters[@type='index'].

• goose_lake: The answer doesn't work for alphabets that contain exemplarCharacters that are more than one JS character, or ones where several diacritics are listed, for example Czech has {ch}, as well as ií and uúů: github.com/unicode-org/cldr/blob/…. So I would suggest using <exemplarCharacters type="index"> instead, and parsing as space separated, and possibly {}-enclosed, array.
• Heiko Theißen: Indeed, the .sort() removes the diacritics, I have taken that out. And thanks for mentioning the type="index", I have included that.
• Heiko Theißen: I think your suggestion deserves to be written down as a separate answer.
• goose_lake: Yep, can write that down in an answer, it's limiting to not have line breaks or full code blocks, so it's very hard to read in the end.

Answer 2

Expanding on the other answer, which suggests to use Unicode CLDR data, while addressing some shortcomings:

Some languages have alphabets that include "letters" that are more than one JS character long, and where some letters are sets with several diacritics (for example Czech has {ch}, as well as ií and uúů in exemplary characters), it would be more convenient to use "index" type exemplar characters, which include only characters used for indexing/searching (note that they are also capitalized). In most cases they split diacritics that are significantly different in the language's use to be considered a different letter. For cases where they don't (i.e. её in Russian), it's best to use only the first variant. Some non-alphabetic languages like Chinese, have a very large set of exemplar characters, but are indexed using a way smaller set, which is likely the best one to use.

With that all in mind, here is a function that gets them and parses them, using a IETF language tag as an input, using the JSON-type CLDR data for simplicity:

async function getCharacters(languageTag) {
 const req = await fetch(`https://raw.githubusercontent.com/unicode-org/cldr-json/refs/heads/main/cldr-json/cldr-misc-full/main/${languageTag}/characters.json`);
 if (!req.ok) {
 return null;
 }
 try {
 const data = await req.json();
 // comes in the form of "[A B C {CH} IÍ]"
 const indexCharactersString = data.main?.[languageTag]?.characters?.index;
 if (!indexCharactersString) {
 return null;
 }
 const alphabetArray = indexCharactersString
 // removes []
 .substring(1, indexCharactersString.length - 1)
 // split by space, after we have either single-character letters, multi-character letters in {}, or diacritic sets like ЕЁ
 .split(" ")
 // for {}-encased letters, return everything inside {}, for non-{} letters, it's either a character or a diacritic set, so we just take the first character
 .map(char => char.startsWith("{") ? char.substring(1, char.length - 1) : char.substring(0,1));
 return alphabetArray;
 }
 catch(e) {
 return null;
 }
}
getCharacters("cs").then(arr => console.log(arr));

Any valid language tag that exists in the CLDR will return the alphabet, and non-existing ones will return null.