1388777 - Array.prototype.toLocaleString should use a locale-aware separator

Status: RESOLVED INACTIVE

(Core :: JavaScript: Internationalization API, defect, P3)

Description

[silv3rwind]

Attachment: window-regional-settings.png

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:55.0) Gecko/20100101 Firefox/55.0
Build ID: 20170803105720

Steps to reproduce:

On a Windows machine and a german locale with default regional settings set, run this in the browser console:

['',''].toLocaleString()


Actual results:

Output is ','


Expected results:

Output should be ';'

The spec [1] says "the list-separator String appropriate for the host environment’s current locale", and this value is a setting in the Windows regional options (see attached screenshot). The implementation of using this value should be similiar to how Number.prototype.toLocaleString already works for the locale-aware decimal point formatting.

Also to mention: Chrome exhibits the same bug. IE11 and presumably Edge return '; ' on the tested system, which is closes to the expected ';'.

[1] https://tc39.github.io/ecma402/#sup-array.prototype.tolocalestring

Comment 1

[silv3rwind]

Chromium bug for reference: https://bugs.chromium.org/p/chromium/issues/detail?id=753841

Comment 2

[André Bargull [:anba]]

(In reply to silv3rwind from comment #0)
> The spec [1] says "the list-separator String appropriate for the host
> environment’s current locale", and this value is a setting in the Windows
> regional options (see attached screenshot).

The sensible choice would be to use a separator string based on the locale-argument resp. the default locale if no explicit locale argument was provided. That way |[1.1, 2.2, 3.3].toLocaleString("en")| would return |"1.1,2.2,3.3"|, and |[1.1, 2.2, 3.3].toLocaleString("de")| would return |"1,1;2,2;3,3"|. Maybe https://github.com/tc39/ecma402/issues/33 will help to get this right in the spec.

Comment 3

[Zibi Braniecki [:zbraniecki][:gandalf]]

Correct, 

Intl.ListFromatter spec proposal aims to add the correct behavior for localized list formatting.

Comment 4

[silv3rwind]

Isn't the intention of the .toLocaleString to format in the user's current locale when no argument is given? It's how Number.prototype.toLocalString works, and I think the Array variant should work the same. 

To shed some light on my use case: I'm trying to find the separator to generate a CSV file for Excel which expects ';' separators when running under a german locale. Right now I've found a workaround using Number.prototype.toLocalString to detect the user's decimal separator, but it's not really ideal as it isn't aware of separators other than ',' and ';' [1].

[1] https://github.com/silverwind/save-csv/blob/46e1883cbe92ca9635f2edd23c2756aec9c717ce/save-csv.js#L25-L31

Comment 5

[Zibi Braniecki [:zbraniecki][:gandalf]]

> Isn't the intention of the .toLocaleString to format in the user's current locale when no argument is given? It's how Number.prototype.toLocalString works, and I think the Array variant should work the same. 

No. Number.prototype.toLocaleString is specified in ECMA262 as dummy no-op, and then as part of Intl.NumberFormat ECMA402 spec as a fully functional localized formatter.

The same has to happen with Intl.ListFormat and Array.prototype.toLocaleString.

> To shed some light on my use case: I'm trying to find the separator to generate a CSV file for Excel which expects ';' separators when running under a german locale.

If I were trying to solve that, I'd probably extract the bits from https://github.com/unicode-cldr/cldr-misc-modern/blob/master/main/de/listPatterns.json for all locales into a single json and use that.

Probably, listPattern-type-unit['middle].

It'll be interesting to see how this will pan out in Intl.ListFormat because the default proposed formatter would get you a human readable list. If this will stay true for Array.prototype.toLocaleString then by default you'll get:

["Anna", "Mary", "Joe"].toLocaleString(); // "Anna, Mary and Joe"

and you'll need to specify "style: unit" option to get "Anna, Mary, Joe"