Unexpected output of Intl.NumberFormat#format with locale "it-IT"

[gabrieleborelli]

Version

v20.19.0

Platform

Linux XXX x.xx.xxx.x-microsoft-standard-WSL2 #1 SMP Fri Mar 29 23:14:13 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux

Subsystem

No response

What steps will reproduce the bug?

Intl.NumberFormat("it-IT").format(1234.56);

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

Always

What is the expected behavior? Why is that the expected behavior?

The expected output is "1.234,56"

The previous node version 20.18.x formatted the number with the thousands separator.

What do you see instead?

I see the output "1234,56"

Between 20.18.x and 20.19.0 the output changed from "1.234,56" to "1234,56".

Now the thousands separator is missing.

Additional information

Adding one more digit the thousands separator is correctly showed.

So it seems the bug occurs only in the range 1000 < x < 9999

[richardlau]

This is related to CLDR changes in ICU 76.1.
Refs:

• Intl.NumberFormat("it-IT").format is returning an incorrectly formatted value in 22.12.0 #56134
• https://unicode-org.atlassian.net/browse/ICU-22985