interface Counter {
    (start: number): string;
    interval: number;
    reset(): void;
}

function getCounter(): Counter {
    let counter = <Counter>function (start: number) { };
    counter.interval = 123;
    counter.reset = function () { };
    return counter;
}

为什么上面接口规定 counter 函数返回string，但实际上counter 函数并没有返回，不报错

interface Counter {
    (start: number): void;
    interval: number;
    reset(): void;
}

function getCounter(): Counter {
    let counter = <Counter>function (start: number) { return '12'};
    counter.interval = 123;
    counter.reset = function () { };
    return counter;
}

但是 我将接口和函数返回调换了一下就报错了