Feature Request: Built-in helpers for getLocaleFromRequest

[ratsclub]

Problem

Almost every Hydrogen project that supports some internationalization needs to implement a custom getLocaleFromRequest utility function. These custom functions often have multiple fallback rules around domain TLDs, subdomains, cookies, headers and path matching.

Proposal

It would be great if Hydrogen shipped built-in utility functions (or a configurable helper) to handle locale detection from a request. This could support multiple detection strategies out of the box (URL path, subdomain, domain, Accept-Language header, cookies) and integrate cleanly with the i18n option in createStorefrontClient.

A starting point?

I've built a small library request-locale that tackles this problem using the standard Web Request API and a few composable functions. It could serve as a reference or starting point for a built-in solution.

const US = {language: 'EN', country: 'US'}
const locales = {
  fr: {language: 'FR', country: 'FR'},
  de: {language: 'DE', country: 'DE'},
};

const isDev = anyOf(isLocal, isPreviewDomain());

getLocaleFromRequest({
  defaultLocale: US,
  strategies: [
    // Use path prefixes during development
    when(isDev, fromPathPrefix(locales)),
    // Only use subdomain locales in production
    whenNot(isDev, fromSubdomain(locales)),
    // Get locale from cookies
    fromCookie("locale", locales),
    // Get locale from Accept-Language header
    fromAcceptLanguageHeader(locales),
  ],
});

Happy to contribute or discuss the API design further. Would love to hear the team's thoughts on this!