First, you need to understand that a promise is executed at the time of creation.
So for example if you have a code:
["a","b","c"].map(x => returnsPromise(x))
You need to change it to:
["a","b","c"].map(x => () => returnsPromise(x))
Then we need to sequentially chain promises:
["a", "b", "c"].map(x => () => returnsPromise(x))
.reduce(
(before, after) => before.then(_ => after()),
Promise.resolve()
)
executing after()
, will make sure that promise is created (and executed) only when its time comes.