Three ways to handle concurrent API requests that resolve when all are done, but can run concurrently.

In other words, if you have three requests and

1. takes 2 seconds,
2. takes 1 second
3. takes 2 seconds

They should return together in 2 seconds, not five.

PHP:

React\Promise\all([$promise1, $promise2])->then(function ($results) {
    // $results is an array of the resolved values from all promises
});

Javascript:

Promise.all([promise1, promise2]).then((results) => {
    // results is an array of the resolved values from all promises
});

Python:

results = await asyncio.gather(task1(), task2())

Each of those (all, all, gather) return a new promise that resolves when everything in it (it == all, all, or gather) is finished/resolved.

Then, you have the result of all three and can move on to the next step. You could also do them one by one, but it would take longer.