Unify defining number formats for different locales

[MickL]

Clear and concise description of the problem

At the moment number formats need to be defined for every locale, but this results in duplicate code:

numberFormats: {
    de: {
      currency: {
        style: 'currency',
        currency: 'EUR',
      },
    },
    fr: {
      currency: {
        style: 'currency',
        currency: 'EUR',
      },
    },
    es: {
      currency: {
        style: 'currency',
        currency: 'EUR',
      },
    },
  },
  datetimeFormats: {
    de: {
      date: {
        year: 'numeric',
        month: '2-digit',
        day: '2-digit',
      },
    },
    fr: {
      date: {
        year: 'numeric',
        month: '2-digit',
        day: '2-digit',
      },
    },
    es: {
      date: {
        year: 'numeric',
        month: '2-digit',
        day: '2-digit',
      },
    },
  },

This is a simple example but imagine having 27 EU countries and defining multiple date formats and all of them are the same.

Suggested solution

Maybe something like this:

numberFormats: {
    currency: {
      style: 'currency',
      currency: 'EUR',
      locales: ['de', 'fr', 'es'],
    },
  },
  datetimeFormats: {
    date: {
      year: 'numeric',
      month: '2-digit',
      day: '2-digit',
      locales: ['de', 'fr', 'es'],
    },
  },

Additionally locales could be optional: If not defined it applies to all locales.

Alternative

No response

Additional context

No response

Validations

• Read the Contributing Guidelines
• Read the Documentation
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[razorness]

A workaround is this:

const datetimeFormats: {
    de: {
      date: {
        year: 'numeric',
        month: '2-digit',
        day: '2-digit',
      },
    }
};

datetimeFormats['fr'] = datetimeFormats.de;
datetimeFormats['es'] = datetimeFormats.de;

[MickL]

True! Only downside is it creates duplicate code in the final bundle. Not much but depends on how many formats and languages. Also the compiler complains, in your example that fr and es is missing.