Benchmark: get value from dict of array

Script Preparation code:

var arr = Array(100).fill({data:Array(100).fill(0)})

Tests:

flatMap
arr.flatMap(x => x.data)
flatMap2
arr.flatMap(({data}) => data)
map then flat
arr.map(({data}) => data).flat()

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
flatMap
flatMap2
map then flat

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/110.0.0.0 Safari/537.36

Browser/OS: Chrome 110 on Windows

View result in a separate tab

Test name	Executions per second
flatMap	958.8 Ops/sec
flatMap2	972.7 Ops/sec
map then flat	969.1 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**What is tested?**

The provided JSON represents three individual test cases for a JavaScript benchmark, measuring the performance of different approaches to flatten an array of arrays using the `flatMap` method.

**Options compared:**

Three options are compared:

1. **`arr.flatMap(x => x.data)`**: This approach uses the spread operator (`...`) and the `flatMap` method with a callback function that takes each element of the inner array as its argument.
2. **`arr.flatMap(({data}) => data)`**: This approach uses destructuring assignment to extract the `data` property from each object in the inner array, and then applies the spread operator (`...`) to flatten the result.
3. **`arr.map(({data}) => data).flat()`**: This approach uses the `map` method to create a new array with the same number of elements as the original array, but with each element being the flattened version, and then calls the `flat()` method to remove the wrapping array.

**Pros and Cons:**

1. **`arr.flatMap(x => x.data)`**: Pros:
	* Simple and concise syntax.
	* Fast, since it avoids creating intermediate arrays.
Cons:
	* Can be slower than other approaches for very large inputs, due to the overhead of applying a callback function to each element.
2. **`arr.flatMap(({data}) => data)`**: Pros:
	* More readable syntax, as it clearly expresses the intent to flatten an array of objects using destructuring assignment.
Cons:
	* Can be slower than other approaches, since it creates intermediate arrays during the flattening process.
3. **`arr.map(({data}) => data).flat()`**: Pros:
	* Easy to understand and implement for developers familiar with `map` and `flat` methods.
Cons:
	* Creates intermediate arrays, which can lead to slower performance compared to other approaches.

**Library usage:**

None of the benchmark test cases use any external libraries. The tests only rely on built-in JavaScript features.

**Special JS feature or syntax:**

The `flatMap` method is a relatively new feature introduced in ECMAScript 2019 (ES10). It allows flattening arrays in a more concise and expressive way than traditional methods like `map()` followed by `flat()`. The test cases take advantage of this feature to benchmark different approaches.

**Other alternatives:**

If you want to explore alternative approaches, here are a few options:

* **`reduce()`**: You can use the `reduce()` method in combination with an accumulator function to flatten an array of arrays. This approach can be more expressive and flexible than `flatMap()`, but it may also incur higher overhead due to the need for multiple iterations.
* **`Array.prototype.flat()`**: If you're using a modern browser or a Node.js version that supports `flat()` method, you can use this built-in method to flatten an array of arrays. This approach is often faster than other methods, but it may not work in older browsers or environments.

In summary, the provided benchmark test cases measure the performance of different approaches to flatten an array of arrays using the `flatMap` method, highlighting the trade-offs between conciseness, readability, and performance.

Related benchmarks:

get value from dict of array (version: 0)

Comparing performance of: flatMap vs flatMap2 vs map then flat

Created: one year ago by: Guest

Jump to the latest result

flatMap

flatMap2

map then flat

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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