Why does this resolved Q promise responds to valueOf with a promise?

为什么这个解决问承诺响应返回对象的值一个承诺吗？

youdao

And, just like Iterable and Enum, the valueOf methods are not present in the JDK 1.4 class library.

而且，就像Iterable和Enum一样，value Of方法在JD K 1.4类库中也不存在。

youdao

The solution is to use the valueOf method on the Date object to see how long it has been since the start of the animation.

解决方案是使用Date对象的value Of方法确定动画开始了多长时间。

youdao