i18n.js

const i18n = { 
  create: function () {
    this.interpolate = (template, fillers) => {
      let ret = template;
        for (const key of Object.keys(fillers)) {
            ret = ret.replace(`{${key}}`, fillers[key])
        }
      return ret;
    };

    this.t = (lookupStr, fillers) => {
      const lookupKeys = lookupStr.split('.');
      let translation = this.translations;
      for (let i = 0; i < lookupKeys.length; i++) {
        translation = translation[lookupKeys[i]];
      }

      if (!fillers) {
        return translation;
      } else {
        return this.interpolate(translation, fillers);
      }
    };

    this.translations = {
      homePage: {
        footer: {
          copyright: 'Copyright {companyName} 2019'
        }
      }
    };

    return this;
  }
}