如何继续等待一个功能完成？

Question

I have three functions. The calling hierarchy is like this:

function a() {
    b();
    c();
}

function b() {
    d();
}

What I want is to finish b then continue doing c. But d is asynchronous. I don't have rights to change anything in b and d. Is there any way to handle this case? Sorry for my English.

Answer 1

Almost certainly not. You need a callback, a promise, or an event.

Since you can't change b() , you can't add a callback argument to d() (assuming it accepted one in the first place) and you can't capture the return value of d() (assuming it returned a promise in the first place).

We have no way of telling if d() triggers an event on the DOM when it is done (or even if you are running the JS in a context where there is a DOM).