NumberFormat: new option to force sign

[ray007]

Intl.NumberFormat could use an option to also show a sign ("+") for positive numbers.

[caridy]

We need a formal proposal, and a champion :)

[littledan]

This does sound potentially useful. I have a few questions for the next steps:

• Do you think you could list some cases where you'd want to use this option?
• Is it really something that you want to be an option that the user chooses, or is this something that turns on in some locales and not in others?
• How is this option represented in other locale data repositories, e.g., ICU and CLDR?

cc @jungshik

[ray007]

• It may not be needed often, but some of our customer have asked for it. I missed it for formatting ISO8601 timezone offsets.
• I don't think you'd want this always on, but I don't know enough about most locales to judge that.
• It's defined in main/{localeId}/numbers.json, key symbols-numberSystem-latn/plusSign

[anba]

Now possible through the "signDisplay" option:

js> print(new Intl.NumberFormat('en', { signDisplay: "always" }).format(10))                                                
+10

[sffc]

Yep, the proposal is Stage 4 and merged. Closing as Fixed