Plurals

Plural rules vary by language: English has one/other; Russian has one/few/many; Arabic has more categories. ICU MessageFormat and libraries like FormatJS handle `{count, plural, ...}` instead of `if (n === 1)` in application code.

					{count, plural,
  =0 {No messages}
  one {# message}
  few {# messages}
  many {# messages}
  other {# messages}
}
				

| Anti-pattern | Why it fails | |--------------|--------------| | `count + " items"` | Word order and grammar differ | | English rules globally | Slavic and Arabic need extra branches | | Splitting sentence across keys | Translators cannot reorder words |

Keep full sentences in one message id; pass variables for count, names, and gender when grammars require agreement.

On interviews: CLDR plural categories; i18next vs FormatJS; extracting messages for translators; plural + select combined messages.

Common pitfalls: concatenating subject and object separately; missing `=0` branch; not testing `21` in Russian (one form) vs `22` (few); pluralizing in JSX instead of catalog.

The trade-off is translator workflow complexity versus grammatically correct UI in every locale.

Checklist:

• One message owns the whole sentence.
• Use ICU plural/select in catalogs.
• Test 0, 1, 2, 5, 21 across target locales.
• Avoid string math in components.