Review customer name formatting

Review exercise · TypeScript

Review brief

Beginner20 min

A shared account helper now formats customer names for receipts and profile headers. Customers may provide optional name parts and use locales whose conventional family-name order differs.

Behavioral contract

For Japanese, Korean, and Chinese locales, place the family name before the given and middle names; use given-middle-family order elsewhere.
Locale matching uses the language subtag, so values such as `ja-JP` and `zh-Hant-TW` follow family-first ordering.
Trim each part, collapse runs of whitespace inside a part, and omit parts that are empty after normalization.
Preserve the customer's capitalization, punctuation, and Unicode characters.
If every part is absent or blank, return an empty string.

Review instructions

1Review the formatter and tests against the stated name-order and normalization contract.
2Prioritize no more than four findings and distinguish user-visible defects from optional formatting preferences.

Learning objectives

• Apply locale-specific ordering rules
• Normalize whitespace without rewriting user spelling
• Test optional and locale-sensitive inputs

src/customer-name.tsTypeScript

@@ -0,0 +1,31 @@

1+export interface CustomerName {

2+ givenName?: string;

3+ middleName?: string;

4+ familyName?: string;

5+}

7+function clean(part: string): string {

8+ return part.trim();

9+}

10+

11+export function formatCustomerName(

12+ name: CustomerName,

13+ locale: string,

14+): string {

15+ const givenFirst = [name.givenName, name.middleName, name.familyName];

16+ const familyFirst = [name.familyName, name.givenName, name.middleName];

17+

18+ const ordered = locale === "ja" ? familyFirst : givenFirst;

19+

20+ return ordered

21+ .filter((part): part is string => Boolean(part))

22+ .map(clean)

23+ .join(" ");

24+}

25+

26+export function formatCustomerInitials(name: CustomerName): string {

27+ return [name.givenName, name.familyName]

28+ .filter((part): part is string => Boolean(part))

29+ .map((part) => part.trim().slice(0, 1).toUpperCase())

30+ .join("");

31+}

Reference solution

The findings below are ordered by priority.

Findings

1. Region-qualified family-first locales use the wrong name order

Location: src/customer-name.ts:18

The code recognizes only the exact string ja. Values such as ja-JP fall through to given-first order, and Korean and Chinese language tags are never handled. Customers therefore see a culturally incorrect display order for most family-first locale values.

Parse or compare the locale's language subtag and select family-first order for ja, ko, and zh regardless of region or script subtags.

2. Whitespace-only parts leave extra separators

Location: src/customer-name.ts:20-23

The array is filtered before its strings are trimmed. A value containing only spaces passes Boolean, becomes empty in clean, and still contributes a separator to the joined result.

Normalize each part first, including collapsing internal whitespace, and then remove normalized empty strings before joining.

3. Internal whitespace is not normalized

Location: src/customer-name.ts:7-9

trim removes only leading and trailing whitespace. A customer value such as "Mary Jane" keeps the repeated internal spaces even though the display contract requires each run to collapse to one space.

Have the normalization helper replace whitespace runs after trimming while leaving capitalization, punctuation, and Unicode code points unchanged.

4. Tests omit every locale and blank-part boundary

Location: src/customer-name.test.ts:5-22

Both tests use an English locale and nonempty ASCII parts. They cannot detect language-subtag handling, family-first order, whitespace-only parts, internal whitespace, or the all-blank result.

Add table-driven cases for ja-JP, ko, and zh-Hant-TW, plus blank and internally spaced parts and user-provided Unicode capitalization.

Reasonable non-findings

Leaving capitalization and punctuation untouched is intentional; display-name case conversion is not required.
The initials helper is outside the changed display-name contract and does not need to follow the full-name ordering policy.
Transliteration, honorifics, and locale-specific collation are outside this exercise.