A stable/neutral/culture insensitive locale in Javascript?

Question

I would like to have a stable, well defined sort order in Javascript.

It could be any defined locale, but the point is to have the code say "just some neutral sort order used here".

Java and C# have their Neutral culture and ROOT locales which have been used for this purpose.

The Mozilla documentation does not at least immediately seem to offer such options.

When you say sort order, how do you sort for the locale to come into play — by using localeCompare? — Ingo Bürk, Dec 22 '19 at 10:16
@IngoBürk yes. I'm trying to use localeCompare. I noticed that there are other options that could be set — Peter Lamberg, Dec 22 '19 at 10:18
What do you consider "neutral"? Just use the standard string comparison, which is well-defined and culture-insensitive. — Bergi, Dec 22 '19 at 16:16
@Bergi Thanks. I mean precisely that. I didn't know/remember that `<` applies to strings. The sort order is the same as with `sort()` on strings. — Peter Lamberg, Dec 22 '19 at 17:52

Peter Lamberg · Answer 1 · 2020-02-17T07:11:23.557

My answer is to use "en" with localeCompare

Based on my tests below, en produces the most consistent results.

Here is an example of using that with localeCompare:

"å".localeCompare("ä", "en")

By my understanding und (short for undetermined) (and maybe en-US-u-va-posix) should be better answers to the original question, but the und seems to behave differently in Firefox (and the behavior of en-US-u-va-posix in NodeJS depends on the presence of the ICU-data).

Perhaps if you are not hitting the Firefox problem, consider using und or just the parameterless form to convey the idea that the locale is not important

Some related things I learned while researching this (adding them here just in case somebody else is heading down the same rabbit hole):

This very popular answer about using localeCompare with lots of useful comments.
From this old post I learned that there are some "special" locales.
With older browsers there may be no hope. Quoting the Mozilla documentation: "In older implementations, which ignore the locales and options arguments, the locale and sort order used are entirely implementation dependent."
NodeJS seems to use the Project ICU icu4c library under the hood for locale related functionality.
The icu-project has this online tool to experiment with collation orders.
the plain sort() is different from the other options, but seems stable across the platforms I tested.
The characters were triggering some kind of bug on older version of NodeJS
The locale data is not present in my node installation and installing the icu data makes the localeCompare have different behavior.

Here is the test code I ended up using:

const testArray=["Ă","Â","Î","Ș","Ț","A","i","I","S","T","é","e","ä","a","","","Д","д", "å", "z"]
const locales=["POSIX", "en-US-u-va-posix", "und", "en", "da", "ru"]

console.log(`${testArray.sort().join("")} sort()`)

console.log(`${testArray.sort((a,b)=>a.localeCompare(b)).join("")} localeCompare(x)`)

locales.forEach(locale => {
    const f = (a,b) => a.localeCompare(b, locale)
    try{
        console.log(`${testArray.sort(f).join("")} ${locale}`)
    } catch(e) {
        console.log(`${locale}: ${e}`)
    }
})

On my Mac with NodeJS 13.5.0 with full-icu I get this output:

AISTaeizÂÎäåéĂȘȚДд sort()
aAĂÂåäeéiIÎSȘTȚzдД localeCompare(x)
aAĂÂåäeéiIÎSȘTȚzдД POSIX
AĂÂIÎSȘTȚaåäeéizдД en-US-u-va-posix
aAĂÂåäeéiIÎSȘTȚzдД und
aAĂÂåäeéiIÎSȘTȚzдД en
AaĂÂeéIiÎSȘTȚzäåДд da
дДaAĂÂåäeéiIÎSȘTȚz ru

Node v12.14.0 gets the same result.

Without the NODE_ICU_DATA, v12.14.0 gives:

AISTaeizÂÎäåéĂȘȚДд sort()
aAĂÂåäeéiIÎSȘTȚzдД localeCompare(x)
aAĂÂåäeéiIÎSȘTȚzдД POSIX
aAĂÂåäeéiIÎSȘTȚzдД en-US-u-va-posix
aAĂÂåäeéiIÎSȘTȚzдД und
aAĂÂåäeéiIÎSȘTȚzдД en
aAĂÂåäeéiIÎSȘTȚzдД da
aAĂÂåäeéiIÎSȘTȚzдД ru

My Chrome browser gives this result:

AISTaeizÂÎäåéĂȘȚДд sort()
aAĂÂåäeéiIÎSȘTȚzдД localeCompare(x)
aAĂÂåäeéiIÎSȘTȚzдД POSIX
aAĂÂåäeéiIÎSȘTȚzдД en-US-u-va-posix
aAĂÂåäeéiIÎSȘTȚzдД und
aAĂÂåäeéiIÎSȘTȚzдД en
AaĂÂeéIiÎSȘTȚzäåДд da
дДaAĂÂåäeéiIÎSȘTȚz ru

The Safari browser on my mac gives the same except for da:

aAĂÂeéiIÎSȘTȚzäåдД da

Firefox on my mac gives this somewhat different result:

AISTaeizÂÎäåéĂȘȚДд sort()
aAĂÂeéiIÎSȘTȚzåäдД localeCompare(x)
aAĂÂeéiIÎSȘTȚzåäдД POSIX
aAĂÂåäeéiIÎSȘTȚzдД en-US-u-va-posix
aAĂÂeéiIÎSȘTȚzåäдД und
aAĂÂåäeéiIÎSȘTȚzдД en
AaĂÂeéIiÎSȘTȚzäåДд da
дДaAĂÂåäeéiIÎSȘTȚz ru

There is also the function Intl.getCanonicalLocales. Here are some results I found testing that:

$ node
> Intl.getCanonicalLocales("en-US-POSIX")
[ 'en-US-u-va-posix' ]

On recent Chrome it works as above in NodeJS
On recent Safari getCanonicalLocales seems to accept almost any string and returns that string
Recent Firefox is the same as recent Safari

score 1 · Accepted Answer · answered Dec 22 '19 at 17:56

As @Bergi pointed out above, in many cases you can just use < on strings and it is well defined and culture insensitive.

Say for using some kind of custom sort something like this would work:

["foo", "bar"].sort((a, b)=> a < b ? -1 : 1)

(in that simple case .sort() would of course be equivalent and simpler.)

A stable/neutral/culture insensitive locale in Javascript?

2 Answers2

Linked