The type used by custom message functions, if any.
These extend the default functions.
The formatted-parts type used by any custom message values.
Optionaloptions: MessageFormatOptions<T, P>Format a message to a string.
import { MessageFormat } from 'messageformat';
import { DraftFunctions } from 'messageformat/functions';
const msg = 'Hello {$user.name}, today is {$date :date style=long}';
const mf = new MessageFormat('en', msg, { functions: DraftFunctions });
mf.format({ user: { name: 'Kat' }, date: new Date('2025-03-01') });
'Hello Kat, today is March 1, 2025'
OptionalmsgParams: Record<string, unknown>Values that may be referenced by $-prefixed variable references.
To refer to an inner property of an object value,
use . as a separator; in case of conflict, the longest starting substring wins.
OptionalonError: (error: unknown) => voidCalled in case of error. If not set, errors are by default logged as warnings.
Format a message to a sequence of parts.
import { MessageFormat } from 'messageformat';
import { DraftFunctions } from 'messageformat/functions';
const msg = 'Hello {$user.name}, today is {$date :date style=long}';
const mf = new MessageFormat('en', msg, { functions: DraftFunctions });
mf.formatToParts({ user: { name: 'Kat' }, date: new Date('2025-03-01') });
[
{ type: 'text', value: 'Hello ' },
{ type: 'bidiIsolation', value: '\u2068' },
{ type: 'string', source: '$user.name', locale: 'en', value: 'Kat' },
{ type: 'bidiIsolation', value: '\u2069' },
{ type: 'text', value: ', today is ' },
{
type: 'datetime',
source: '$date',
dir: 'ltr',
locale: 'en',
parts: [
{ type: 'month', value: 'March' },
{ type: 'literal', value: ' ' },
{ type: 'day', value: '1' },
{ type: 'literal', value: ', ' },
{ type: 'year', value: '2025' }
]
}
]
OptionalmsgParams: Record<string, unknown>Values that may be referenced by $-prefixed variable references.
To refer to an inner property of an object value,
use . as a separator; in case of conflict, the longest starting substring wins.
OptionalonError: (error: unknown) => voidCalled in case of error. If not set, errors are by default logged as warnings.
A message formatter for that implements the LDML 47 MessageFormat specification as well as the TC39 Intl.MessageFormat proposal.