# Promise.all() — Using Promise.all() with async functions

> Within async functions, it's very common to "over-await" your code.

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## Knowledge

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Within async functions, it's very common to "over-await" your code. For example, given the following functions

You may write a function like this

However, note that the execution of promptForDishChoice and fetchPrices don't depend on the result of each other. While the user is choosing their dish, it's fine for the prices to be fetched in the background, but in the code above, the await operator causes the async function to pause until the choice is made, and then again until the prices are fetched. We can use Promise.all to run them concurrently, so that the user doesn't have to wait for the prices to be fetched before the result is given

Promise.all is the best choice of concurrency method here, because error handling is intuitive — if any of the promises reject, the result is no longer available, so the whole await expression throws.

Promise.all accepts an iterable of promises, so if you are using it to run several async functions concurrently, you need to call the async functions and use the returned promises. Directly passing the functions to Promise.all does not work, since they are not promises.

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