enum Themes { default = 'default', dark = 'dark', } import * as darkThemeConfig from './themes/dark'; import * as defaultThemeConfig from './themes/default'; export default (themeId: Themes) => { if (themeId === Themes.dark) { return Object.assign({}, defaultThemeConfig, darkThemeConfig); } return Object.assign({}, defaultThemeConfig); }; export type Theme = typeof defaultThemeConfig;