Benchmark: filter + flat - MeasureThat.net

Script Preparation code:

var a = [];
for (i=0;i<1000;i++) {if(i%2) a.push(['a','b', 'c']); else a.push(null)}

Tests:

filter before
a.filter(v => v).flat();
flat before
a.flat().filter(v => v);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
filter before
flat before

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

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

**Benchmark Definition**
The benchmark is defined by a script preparation code that creates an array `a` with 1000 elements, where every other element is an array of three strings: `'a'`, `'b'`, and `'c'`. The purpose of this initial setup is to create a realistic scenario for testing the performance of the `filter()` and `flat()` methods.

**Options being compared**
Two different approaches are being compared:

1. **Filter before flat**: This approach tests filtering an array after it's been flattened. In other words, it executes the following JavaScript code: `a.filter(v => v).flat();`.
2. **Flat before filter**: This approach tests flattening an array before filtering it. The corresponding JavaScript code is: `a.flat().filter(v => v);`.

**Pros and Cons of each approach**

1. **Filter before flat**:
	* Pros:
		+ Can be beneficial when the original intent of the programmer was to filter the resulting flattened array.
		+ May reduce memory allocations if the filtering operation can be done on the reduced size.
	* Cons:
		+ Requires an additional memory allocation for the intermediate filtered result, which may not be ideal for performance-critical code paths.
2. **Flat before filter**:
	* Pros:
		+ Reduces memory allocations by filtering the entire original array at once.
		+ Can improve performance if the filtering operation is computationally expensive and can be done on a larger dataset.
	* Cons:
		+ May require additional computation time for filtering, which might offset any potential benefits of reducing memory allocations.

**Library usage**
There is no explicit library mentioned in the benchmark definition or test cases. However, it's worth noting that some JavaScript engines (like V8) have built-in optimizations and performance enhancements for certain array methods, such as `filter()` and `flat()`. These optimizations might influence the results of the benchmark.

**Special JS feature or syntax**
There is no special JavaScript feature or syntax mentioned in the provided code snippet. The code uses standard ECMAScript 2015 features (var, arrow functions, template literals) but does not utilize any experimental or proprietary features.

**Other alternatives**

When comparing performance-critical array operations like filtering and flattening, it's essential to consider other factors beyond just the order of operations:

1. **Array size**: Larger arrays can benefit from approaches that reduce memory allocations.
2. **Filtering vs. mapping**: Depending on the use case, mapping an array (e.g., using `map()`) might be more efficient than filtering, especially if the resulting values are used directly or passed to another method without further processing.
3. **Parallelization**: Some modern JavaScript engines and libraries provide features for parallelizing array operations, which can improve performance on multi-core CPUs.

Keep in mind that benchmarking results can vary depending on the specific use case, hardware, and software configurations being tested.

Related benchmarks:

filter + flat (version: 0)

Comparing performance of: filter before vs flat before

Created: 4 years ago by: Registered User

Jump to the latest result

filter before

flat before

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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