这两个承诺语法之间的区别

Question

I am quite confused between these two ways of returning the promises, could someone please explain the difference? I tried to find some whereabouts on google, but couldn't find the exact match.

var a = Promise.resolve('foo');
return a.then();

vs

return Promise.resolve('foo').then();

Answer 1

There's nothing promise specific about this.

return a.b();

Is the same as:

var c = a;
return c.b();

In this case a is Promise.resolve('foo') .