App interface

export interface App 

name: string;

// The default app's name is "[DEFAULT]"
initializeApp(defaultAppConfig);
console.log(admin.app().name);  // "[DEFAULT]"

// A named app's name is what you provide to initializeApp()
const otherApp = initializeApp(otherAppConfig, "other");
console.log(otherApp.name);  // "other"

options: AppOptions;

const app = initializeApp(config);
console.log(app.options.credential === config.credential);  // true
console.log(app.options.databaseURL === config.databaseURL);  // true