Promise.all: Parallel or Sequential Execution in Node.js?

Question: Does Promise.all(iterable) process promises sequentially or in parallel?

Answer: Promise.all does not execute promises; instead, it merely awaits multiple promises concurrently. The computation and outcome of promises are managed by the code invoking Promise.all.

Question: Is there a way to execute an iterable sequentially in Node.js?

Answer: If you have an iterable of promises, you cannot enforce specific execution order using Promise.all. However, for an iterable of asynchronous functions, you can apply the following reduction:

iterable.reduce((p, fn) => p.then(fn), Promise.resolve())

This method ensures that functions are executed sequentially, with the previous function's result passing to the next function as input.