Is it parallel execution of promises?

Question

JavaScript

There are two prescriptions

const promise1 = new Promise(...)
const promise2 = new Promise(...)

I want to execute them in parallel, what can you say about the difference between these two methods, will the execution be parallel in the first method ?

const [result1, result2] = [await promise1, await promise2]

OR

const [result1, result2] = Promise.all([promise1, promise2])

Answer 1

will the execution be parallel in the first method ?

In your code, parallel execution is done by calling:

const promise1 = new Promise(...)
const promise2 = new Promise(...)

since Promises start executing the executor function right after they are created.
But Promise-based libraries don't work like that, they usually return a Promise on a specific call:
In this case:

// последовательный вызов 
const [result1, result2] = [await someCall(), await someOtherCall()];

// параллельный вызов
const [result1, result2] = Promise.all([someCall(), someOtherCall()]);