Invalid unit argument for Intl.NumberFormat() with electric units (volt, joule…)

I am trying to localize my web application and I cannot manage to make Intl.NumberFormat work with electric units (ampere, ohm, volt, joule…).

In the documentation, they provide some examples and the list of units available.

Though I cannot manage to make it work with the electric units:

// Working
console.log(new Intl.NumberFormat('fr', { style: 'unit', unit: 'second' }).format(1000));

// Failing with Invalid unit argument for Intl.NumberFormat() 'volt'
console.log(new Intl.NumberFormat('fr', { style: 'unit', unit: 'volt' }).format(1000));

Does someone have an idea why?

Answer

From MDN INTL

A subset of units from the full list was selected for use in ECMAScript.

Simple Unit
-----------
acre
bit
byte
celsius
centimeter
day
degree
fahrenheit
fluid-ounce
foot
gallon
gigabit
gigabyte
gram
hectare
hour
inch
kilobit
kilobyte
kilogram
kilometer
liter
megabit
megabyte
meter
mile
mile-scandinavian
milliliter
millimeter
millisecond
minute
month
ounce
percent
petabyte
pound
second
stone
terabit
terabyte
week
yard
year

Pairs of simple units can be concatenated with “-per-” to make a compound unit. There is no default value; if the style is “unit”, the unit property must be provided.

Très cool: Megabytes per second becomes mégaoctets par seconde in French

console.log(
  new Intl.NumberFormat('fr', 
    { style: 'unit', unit: 'megabyte-per-second', 'unitDisplay': 'long' }
).format(1000)
);