调用接口指定的方法时可以使用async / await吗？

Question

Given:

    export interface UserAuthenticator
    {
        async isValid(username: string, password: string): Promise<boolean>
    }

Compiling generates error message TS1070: 'async' modifier cannot appear on a type member.

Answer 1

The async keyword is used on the implementation of the method. It doesn't have any meaning on the interface itself. One implementation of the interface could use async/await in its implementation, and another could just return a Promise without the use of await. Theoretically both styles of implementation could have the same behavior and would both conform to the interface.