npm install @wordpress/i18n --save

import { sprintf, _n } from '@wordpress/i18n';

sprintf( _n( '%d hat', '%d hats', 4, 'text-domain' ), 4 );
// Output: "4 hats"

import { __ } from '@wordpress/i18n';

const greeting = __( 'Hello World', 'my-text-domain' );

import { _x } from '@wordpress/i18n';

const readVerb = _x( 'Read', 'verb', 'my-text-domain' );
const readAdjective = _x( 'Read', 'past participle', 'my-text-domain' );

import { _n } from '@wordpress/i18n';

const message = _n(
	'You have one new message',
	'You have %d new messages',
	5,
	'my-text-domain'
);

import { sprintf, __ } from '@wordpress/i18n';

const message = sprintf(
	__( 'Hello, %s!', 'my-text-domain' ),
	'World'
);
// Output: "Hello, World!"

import { setLocaleData } from '@wordpress/i18n';

setLocaleData(
	{
		'': {
			domain: 'my-text-domain',
			lang: 'es',
		},
		'Hello World': [ 'Hola Mundo' ],
	},
	'my-text-domain'
);

import { isRTL } from '@wordpress/i18n';

if ( isRTL() ) {
	console.log( 'Current locale is right-to-left' );
}

import { createI18n } from '@wordpress/i18n';

const customI18n = createI18n();
customI18n.__( 'Hello', 'my-domain' );

import { subscribe } from '@wordpress/i18n';

const unsubscribe = subscribe( () => {
	console.log( 'Locale data changed' );
} );

// Later...
unsubscribe();