Intl.NumberFormat.format*() supports value argument as number, bigint or string. Corresponding methods in intl-numberformat and its consumers, only support number.

Support for string unlocks formatting high-precision values that would lose precision if converted to number. Also, string argument is well-supported across browsers.

I know we want to stay in compliance with the spec so looking at the relevant parts (e.g. format):

3. Let value be ? ToNumber(value).

and "ToNumber" does prescribe handling for string:

6. If argument is a String, return StringToNumber(argument).

Which implies that "value" can be string.

Should this be supported in this library? I am not sure if this lack of support is intentional or not. If not, please convert this to an issue.