Concurrent promises and result ordering

The idea

Await pauses an async function’s continuation until its operand settles; it does not stop all other JavaScript work. Two independent operations can be started before either is awaited. Promise.all combines them and returns values in input order, even if they finish in another order. By contrast, awaiting one operation before starting the second expresses a dependency and usually loses concurrency.

Choose failure behavior according to the application contract. Promise.all rejects when an input rejects, but this does not automatically cancel the other operations. Promise.allSettled waits for every outcome and reports each as fulfilled or rejected. A tolerant report can use those individual outcomes, while a calculation requiring every input should surface failure. Avoid async callbacks in forEach when the caller needs a promise representing completion of all work.

async function report() {
  const tasks = [Promise.resolve("first"), Promise.resolve("second")];
  const values = await Promise.all(tasks);
  console.log(values.join("/"));
}
report();

first/second

The combined array follows the tasks array order, not a completion race.