Run two functions with Ajax calls sequentially

Question

I have two functions which has ajax calls inside them.

function a(){
    ajaxCall_A();
}
function b(){
    ajaxCall_B();
}

And I

Answer 1

Make sure that ajaxCall_A() and ajaxCall_B() return promises, and add returns to a() and b().

function a(){
    return ajaxCall_A();
}
function b(){
    return ajaxCall_B();
}

Then, a() and b() will execute sequentially as follows :

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

You should also add a return to c() so it returns a promise to its caller.

function c() {
    return a().then(b);
}