A polyfill/ponyfill for Intl.supportedValuesOf.

Installation#

npm i @formatjs/intl-supportedvaluesof

Requirements#

• Intl.Collator
• Intl.DateTimeFormat or polyfill
• Intl.NumberFormat or polyfill.

Usage#

Simple#

import '@formatjs/intl-supportedvaluesof/polyfill.js'

Dynamic import + capability detection#

async function polyfill() {
  // This platform already supports Intl.supportedValuesOf
  if (shouldPolyfill()) {
    await import('@formatjs/intl-supportedvaluesof/polyfill.js')
  }
  // Alternatively, force the polyfill regardless of support
  await import('@formatjs/intl-supportedvaluesof/polyfill-force.js')
}

Tests#

The Bazel :test262 target runs the upstream suite against a reviewed failure baseline. A green baseline check does not mean every test passed. See the conformance report; run bazel test //packages/intl-supportedvaluesof:test262-strict to require zero failures.

Key coercion#

Intl.supportedValuesOf converts its key to a string before validating the category. String wrapper objects are accepted; Symbols throw TypeError.

Intl.supportedValuesOf is callable but cannot be used as a constructor.

Time-zone candidates include the pinned IANA etcetera Zone records and UTC, in addition to continental transition zones. Runtime filtering retains primary identifiers and omits aliases such as Etc/UTC.

Collation enumeration probes CLDR-derived candidate locales for each type, including locale-specific collations such as German phonebk and Spanish trad. Only collations accepted by the installed Collator are returned.