Add strict validation mode for localized numbers in NumberParser

[AnnaYuS]

Thanks for the great work on this package — it’s been super helpful!

Currently, there’s the isValidPartialNumber method, which is recommended to use for validation. However, there’s a tricky case like this:

In a de locale (group separator ".", decimal separator ",") user types 123.45,67:

const parser = new NumberParser({ useGrouping: true });
parser.isValidPartialNumber('123.45,67'); // true
parser.parse('123.45,67'); // 12345.67

The user meant to type 123.450,67, but the parser interprets it differently.
This can silently change the number in an important form without the user noticing (for example if they type and save and never see the changed number after saving)

Would it make sense to add an option like:

const parser = new NumberParser({ useGrouping: true, strictValidation: true });
parser.isValidPartialNumber('123.45,67'); // false

so developers can show a validation message in such cases?
Or is there a recommended “safe and friendly” way to validate localized inputs that avoids this problem?

Thanks again for your work! 🙏

[snowystinger]

I think this is a pretty useful idea.

Linking your other issue in here because I think some of the comments from our thread are relevant #9086

We'll need to determine if grouping validation is the only thing that this changes or if there are other ambiguous cases we're making assumptions on.