Benchmark: flat() vs flatMap()

Script Preparation code:

var arr = Array.from({ length: 9999 }, () => [{a: 1, b: 2, c:3 }, {d: 4, e: 5, f: 6}]);

Tests:

flat()
arr.flat();
flatMap()
arr.flatMap(e => e);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
flat()
flatMap()

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 5 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36

Browser/OS: Chrome 126 on Windows

View result in a separate tab

Test name	Executions per second
flat()	1807.7 Ops/sec
flatMap()	1579.3 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark compares two approaches to flatten an array of objects in JavaScript: `flat()` vs `flatMap()`. The input data is an array of 10,000 objects, each containing multiple properties (a, b, c, d, e, f).

**Options Compared**

Two options are being compared:

1. **`arr.flat()`**: This method uses the spread operator (`...`) to flatten the array.
2. **`arr.flatMap(e => e)`**: This method uses a callback function to iterate over each object in the array and return a new flattened array.

**Pros and Cons of Each Approach**

1. **`flat()`**
	* Pros:
		+ More concise and readable code
		+ Less memory overhead due to not creating intermediate arrays
	* Cons:
		+ Can be slower than `flatMap()` for large datasets, as it uses the spread operator which creates a new array
2. **`flatMap()`**
	* Pros:
		+ Generally faster than `flat()`, especially for large datasets
		+ More flexible, as it allows for custom iteration logic
	* Cons:
		+ More verbose code compared to `flat()`
		+ Creates an intermediate array, which can increase memory overhead

**Library and Special JS Feature**

There is no explicit library mentioned in the benchmark. However, both methods are built-in JavaScript methods.

If you're interested in exploring alternative approaches, some options include:

1. **`Array.prototype.reduce()`**: This method can be used to flatten an array by accumulating the values from each object.
2. **`lodash.flat()`**: If you're using the Lodash library, you can use `_.flat()` which is a more concise and readable way to flatten an array.

**Other Considerations**

When writing benchmarks like this one, it's essential to consider factors such as:

1. **Dataset size**: The size of the input data can significantly impact performance.
2. **Platform and browser**: Different platforms and browsers may exhibit varying performance characteristics due to differences in JavaScript engines, memory management, and other factors.
3. **Optimization techniques**: Optimizations like caching, memoization, or parallel processing may affect performance.

In this benchmark, the results indicate that `flatMap()` is generally faster than `flat()`, especially for large datasets. However, the actual performance difference will depend on the specific use case, dataset size, and platform being tested.

Related benchmarks:

flat() vs flatMap() (version: 0)

Comparing performance of: flat() vs flatMap()

Created: 5 months ago by: Guest

Jump to the latest result

flat()

flatMap()

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):