consistent-plural-format.md

consistent-plural-format

Enforce consistent format for plural definitions in Lingui i18n library.

Rule Details

This rule enforces a consistent format for plural definitions when using the plural() function or <Plural> component from Lingui. There are two supported formats:

1. Hash format (default): Uses # as a placeholder for the count
2. Template format: Uses template literals with explicit variable interpolation

The rule works with both:

• plural() function calls
• <Plural> React component attributes

Options

This rule accepts an options object with the following properties:

• style (string): The preferred style for plural definitions. Can be either "hash" or "template". Default is "hash".

{
  "lingui/consistent-plural-format": ["error", { "style": "hash" }]
}

Examples

❌ Incorrect (when style is "hash" - default)

plural(numBooks, {
  one: `${numBooks} book`,
  other: `${numBooks} books`,
})

plural(count, {
  zero: `${count} items`,
  one: '# item',
  other: `${count} items`,
})

// String with template literal pattern
plural(numBooks, {
  one: '${numBooks} book',
  other: '# books',
})
;<Plural
  value={messagesCount}
  one={`There's ${messagesCount} message in your inbox`}
  other={`There are ${messagesCount} messages in your inbox`}
/>

✅ Correct (when style is "hash" - default)

plural(numBooks, {
  one: '# book',
  other: '# books',
})

plural(count, {
  zero: '# items',
  one: '# item',
  other: '# items',
})
;<Plural
  value={messagesCount}
  one="There's # message in your inbox"
  other="There are # messages in your inbox"
/>

❌ Incorrect (when style is "template")

plural(numBooks, {
  one: '# book',
  other: '# books',
})

plural(count, {
  zero: '# items',
  one: `${count} item`,
  other: '# items',
})
;<Plural
  value={messagesCount}
  one="There's # message in your inbox"
  other="There are # messages in your inbox"
/>

✅ Correct (when style is "template")

plural(numBooks, {
  one: `${numBooks} book`,
  other: `${numBooks} books`,
})

plural(count, {
  zero: `${count} items`,
  one: `${count} item`,
  other: `${count} items`,
})
;<Plural
  value={messagesCount}
  one={`There's ${messagesCount} message in your inbox`}
  other={`There are ${messagesCount} messages in your inbox`}
/>