Unexpected output of `Intl.NumberFormat#formatRange` with `percent` style for same values

[mdashlw]

Version

v19.3.0

Platform

Microsoft Windows NT 10.0.22621.0 x64

Subsystem

No response

What steps will reproduce the bug?

const percentFormatter = new Intl.NumberFormat("en-US", { style: "percent" });

console.log(percentFormatter.formatRange(0.5, 0.55));
console.log(percentFormatter.formatRange(0.5, 0.5));

How often does it reproduce? Is there a required condition?

all the time for all locales

What is the expected behavior?

50% – 55%
~50%

Similar to:

const numberFormatter = new Intl.NumberFormat("en-US");

console.log(numberFormatter.formatRange(50_000, 55_000)); // 50,000–55,000
console.log(numberFormatter.formatRange(50_000, 50_000)); // ~50,000

What do you see instead?

50% – 55%
~5,000%

Additional information

maximumFractionDigits behavior:

> percentFormatter = new Intl.NumberFormat("en-US", { style: 'percent' });
NumberFormat [Intl.NumberFormat] {}
> percentFormatter.formatRange(0.1234, 0.1234)
~1,200%

> percentFormatter = new Intl.NumberFormat("en-US", { style: 'percent', maximumFractionDigits:10 });
NumberFormat [Intl.NumberFormat] {}
> percentFormatter.formatRange(0.1234, 0.1234)
~1,234%

[targos]

I can confirm the results, but if it's a bug it will have to be fixed in the V8 engine or in ICU. Chromium has the same behavior.

/cc @nodejs/i18n-api

[srl295]

/cc @sffc

[sffc]

@FrankYFTang Any idea if this is a V8 bug? I haven't tested ICU yet, but there are plenty of ICU tests around this behavior so I would be surprised if it is in ICU.

[github-actions]

This issue has been marked as stale due to 210 days of inactivity.
It will be automatically closed in 30 days if no further activity occurs. If this is still relevant, please leave a comment or update it to keep it open.

[mdashlw]

This is no longer reproducible in Node LTS/Current (v24.17.0/v26.3.0) and latest Chrome (149.0.7827.156).

Quick testing reveals this was fixed specifically in v20.20.1 which updated ICU to 78 (#60523).

Related Bugzilla bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1917065
Tracked down the upstream issue: ICU-22937 and ICU-23110 (fix: unicode-org/icu#3483).