Quick and dirty i18n lib

Babelfish.ts

let i18nStrings: Object, currentLanguage: string;

// Replace ${var} with {var: 'This Value'}
function simpleStrReplace(str, replace = {}, failWithThrow = false) {
    return str.replace(/\$\{(.*?)\}/g, (match) => {
        match = match.substring(2, match.length - 1);
        return replace[match] || `??[${match}]??`;
    });
}

function findString(id, lang: string) {
    return i18nStrings[lang[id]] || `??[${id}][${lang}]??`;
}

/**
 * Initialises Babelfish with default values
 * @example
 *  import Babelfish from './Babelfish'
 *  let t = Babelfish({no: {one: 'en', two: 'to'}}, 'no');
 * @param languages Object containing languages to register
 * @param currentLang Default current language
 * @returns {Function} The t (translate) function
 */
export default function Babelfish(languages, currentLang): Function {
    i18nStrings = languages;
    currentLanguage = currentLang;
    return this.t;
}

/**
 * Get current language
 * @return {String}
 */
export function getLanguage(): string {
    return currentLanguage;
}

/**
 * 
 * @param lang Set current language
 */
export function setLanguage(lang: string): void {
    currentLanguage = lang;
}

/**
 * Register string object for new language
 * @param langCode 
 * @param lang 
 */
export function registerLanguage(langCode: string, lang: Object): void {
    i18nStrings[langCode] = lang;
}

/**
 * 
 * @param id Key to look up string
 * @param props Replacement values for string
 * @param language (default: currentLanguage) The language to look up for
 */
export function t(id: string, props: Object, language = currentLanguage): string {
    const str = findString(id, language);
    const returnStr = simpleStrReplace(str, props);

    return returnStr;
}