react-gettext/src/gettext.js

Gettext implementation for React based project.

const DELIMITER = '\u0004'; // End of Transmission (EOT)

function getTranslations(catalog) {
	return typeof catalog === 'function' ? catalog() : catalog;
}

function getPluralForm(plural, n) {
	// return 0 if n is not integer
	if (Number.isNaN(parseInt(n, 10))) {
		return 0;
	}

	// if pluralForm is function, use it to get plural form index
	if (typeof plural === 'function') {
		return plural(n);
	}

	// if pluralForm is string and contains only "n", "0-9", " ", "!=?:%+-/*><&|()"
	// characters, then we can "eval" it to calculate plural form
	if (typeof plural === 'string' && !plural.match(/[^n0-9 !=?:%+-/*><&|()]/i)) {
		/* eslint-disable no-new-func */
		const calcPlural = Function('n', `return ${plural}`);
		/* eslint-enable no-new-func */
		return +calcPlural(n);
	}

	return 0;
}

export function gettext(catalog, message) {
	const messages = getTranslations(catalog);
	return Object.prototype.hasOwnProperty.call(messages, message)
		? messages[message]
		: message;
}

export function ngettext(catalog, plurality, singular, plural, n) {
	const messages = getTranslations(catalog);
	const pluralIndex = getPluralForm(plurality, n);
	const defaultValue = n > 1 ? plural : singular;

	return Object.prototype.hasOwnProperty.call(messages, singular)
			&& Array.isArray(messages[singular])
			&& messages[singular].length > pluralIndex
			&& pluralIndex >= 0
		? messages[singular][pluralIndex]
		: defaultValue;
}

export function xgettext(catalog, message, context) {
	const messages = getTranslations(catalog);
	const key = context + DELIMITER + message;

	return Object.prototype.hasOwnProperty.call(messages, key)
		? messages[key]
		: message;
}

export function nxgettext(catalog, plurality, singular, plural, n, context) {
	const messages = getTranslations(catalog);
	const pluralIndex = getPluralForm(plurality, n);
	const defaultValue = n > 1 ? plural : singular;
	const key = context + DELIMITER + singular;

	return Object.prototype.hasOwnProperty.call(messages, key)
			&& Array.isArray(messages[key])
			&& messages[key].length > pluralIndex
			&& pluralIndex >= 0
		? messages[key][pluralIndex]
		: defaultValue;
}

export default {
	gettext,
	ngettext,
	xgettext,
	nxgettext,
};