Benchmark: async for vs promise.all

Script Preparation code:

async function asyncFor(){
    for (const x of [1, 2, 3]) {
        await new Promise(resolve => resolve(x > 0));
    }
}

async function asyncPromiseAll() {
    await Promise.all([1, 2, 3].map(x =>
        new Promise(resolve => resolve(x > 0))
    ));
}

Tests:

asyncFor
asyncFor()
asyncPromiseAll
asyncPromiseAll()

Historical Performance Data aggregated from 27 community runs

Desktop Results:

Chrome 22 runs

asyncFor

3.4M/s

asyncPromiseAll

1.2M/s

Fastest: asyncFor (2.8x faster)

View exact numbers

✓ asyncFor: 3,435,884 ops/sec
• asyncPromiseAll: 1,232,857 ops/sec

Mobile Results:

Chrome 5 runs

asyncFor

1.0M/s

asyncPromiseAll

472K/s

Fastest: asyncFor (2.2x faster)

View exact numbers

✓ asyncFor: 1,043,827 ops/sec
• asyncPromiseAll: 472,458 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
asyncFor
asyncPromiseAll

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 8 months ago)

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/142.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 142 on Android

View result in a separate tab

asyncFor

2.5M/s

asyncPromiseAll

900K/s

View exact numbers

Test name	Executions per second
✓ asyncFor	2,539,539 Ops/sec
asyncPromiseAll	900,348 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

I'd be happy to help explain the provided benchmark.

**Benchmark Overview**

The benchmark compares two approaches for iterating over an array: `async for` and `Promise.all`. Both approaches use the same logic, but with different implementation details.

**What is being tested?**

The benchmark tests how long it takes for each approach to execute a set of iterations. In this case, the test iterates over an array `[1, 2, 3]`, performing some asynchronous operation (`new Promise(resolve => resolve(x > 0))`) on each element.

**Options compared:**

* `async for`: uses the `for...of` loop with a `await` keyword to wait for each iteration to complete.
* `Promise.all`: uses an array of promises, where each promise resolves when its corresponding element is greater than 0.

**Pros and Cons:**

* **async for**:
	+ Pros: Easy to read and write, intuitive syntax. Waits for each iteration to complete before moving on, which can be beneficial in concurrent programming.
	+ Cons: Can lead to performance issues if the loop is very large or has many iterations, since it waits for each iteration to complete. Additionally, JavaScript's execution context switching can introduce additional overhead.
* **Promise.all**:
	+ Pros: Scalable and efficient way to handle multiple iterations concurrently. Reduces the number of times the callback function needs to be executed.
	+ Cons: More complex syntax, harder to read and understand for some developers. Requires careful consideration of promise chaining and handling potential errors.

**Library usage**

There is no explicit library mentioned in the benchmark definition or test cases. However, it's worth noting that `Promise.all` relies on JavaScript's built-in support for promises, which is a key feature introduced in ECMAScript 2015 (ES6).

**Special JS features**

No special JavaScript features are used beyond what's standard in modern JavaScript.

**Other alternatives**

If the benchmarkers wanted to explore other approaches, they might consider:

* **Traditional `for` loop**: This approach would use a traditional `for` loop with an index variable and manual promise handling.
* **Fibers**: In some environments (e.g., Node.js), developers can use Web Workers or fibers for concurrent execution. However, this approach is not directly applicable to the provided benchmark.
* **Async iterators**: Another option would be to use async iterators, which allow for more efficient iteration over arrays while still supporting asynchronous operations.

Overall, the benchmark provides a clear comparison of two popular approaches for iterating over arrays in JavaScript, allowing developers to evaluate performance characteristics and make informed decisions based on their specific needs.

async for vs promise.all (version: 0)

Comparing performance of: `asyncFor vs asyncPromiseAll`

Created: 5 years ago by: Guest

Go to the latest result

asyncFor

asyncPromiseAll

Historical Performance Data aggregated from 27 community runs

Desktop Results:

Chrome 22 runs

Mobile Results:

Chrome 5 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

async for vs promise.all (version: 0)

Comparing performance of: asyncFor vs asyncPromiseAll

Created: 5 years ago by: Guest

Go to the latest result

asyncFor

asyncPromiseAll

Historical Performance Data aggregated from 27 community runs

Desktop Results:

Chrome 22 runs

Mobile Results:

Chrome 5 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

Related benchmarks

Comparing performance of: `asyncFor vs asyncPromiseAll`