fix: use libphonenumber getRegionCodeForNumber for NANP area codes (787->PR, 809->DO, ...)

[gaoflow]

Summary

parsePhone() returns a self-contradictory result for many NANP (North American Numbering Plan) numbers. For example:

parsePhone("17871234567")
// { countryCode: "1", areaCode: "787", number: "1234567", countryISOCode: "nothing" }

The areaCode: "787" is correct — Puerto Rico — and it was parsed by the bundled libphonenumber. Yet countryISOCode: "nothing". The library contradicts its own bundled libphonenumber, whose getRegionCodeForNumber() returns "PR" for the same input.

The library is even inconsistent with itself: the overlay 939 resolves to "PR" (it is in the prefixes table) while the primary 787 resolves to "nothing" (it is not). Same country, opposite answers.

Root cause

countryISOCode is derived from a hand-rolled, incomplete prefixes table via findCountryISO2, which walks prefixes of the input and looks them up in the map. NANP numbers under country code 1 are listed per-area-code (e.g. 1849: "DO", 1939: "PR"), but many area codes are missing:

Input	Actual	Expected (NANPA + bundled libphonenumber)
17871234567	nothing	PR (787 Puerto Rico)
18091234567	nothing	DO (809 Dominican Republic)
18291234567	nothing	DO (829 Dominican Republic overlay)
12681234567	nothing	AG (268 Antigua & Barbuda)
1284…, 1340…, 1649…, 1784…, 1868…, 1869…	nothing	VG, VI, TC, VC, TT, KN

All of these missing area codes are already known to the bundled libphonenumber, which the package uses to parse areaCode into the very same result object.

Fix

Prefer the bundled libphonenumber's authoritative region. After parsing the number with the existing default region, override countryISOCode with PhoneNumberUtil.getRegionCodeForNumber(r) when it returns a non-null region, falling back to the prefixes table only when libphonenumber cannot determine a region (e.g. invalid numbers). This keeps countryISOCode consistent with the areaCode libphonenumber already parses.

         var t = i18n.phonenumbers.PhoneNumberUtil.getInstance()
           , n = findCountryISO2(e)
           , o = t.getRegionCodeForCountryCode(n)
           , r = t.parseAndKeepRawInput("+" + e, o)
           , d = o = null
           , i = t.getNationalSignificantNumber(r)
           , N = t.getLengthOfNationalDestinationCode(r);
+        var regionForNumber = t.getRegionCodeForNumber(r);
+        null != regionForNumber && (n = regionForNumber);

The prefixes table and findCountryISO2 are retained as the fallback path and to compute the initial default region for parsing, so non-NANP numbers (e.g. +268 Eswatini → SZ) and libphonenumber-null cases are unaffected.

Tests

Added test.js (node assert; the package previously had no test suite — npm test was a stub). Covers:

• RED cases (now fixed): 1787→PR, 1809→DO, 1829→DO, 1268→AG, plus 1284→VG, 1340→VI, 1649→TC, 1784→VC, 1868→TT, 1869→KN.
• Controls (preserved): 1939→PR, 1849→DO, 1202→US.
• Internal consistency: parsePhone("17871234567") has areaCode === "787" AND countryISOCode === "PR" (the original self-contradiction is gone).
• Non-NANP regression guard: parsePhone("26822171234").countryISOCode === "SZ" (Eswatini, country calling code +268, unchanged).

$ node test.js
All tests passed.

Scope

Only index.js (2 lines) and a new test.js. findCountryISO2, the prefixes table, and the bundled libphonenumber metadata are unchanged. No new dependencies.