Benchmark: JS Map + filter vs ForEach

Script Preparation code:

function A(iterations) {
	return new Array(iterations).filter((_, idx) => idx%2 === 0).map((_, idx) => 'hi, i forgot why I am here');
}

function B(iterations) {
  const emptyArray = [];
  new Array(iterations).forEach((_, idx) => {
  	if(idx%2===0) {
    	emptyArray.push('hi, i forgot why I am here');
    }
  })
  return emptyArray;
}

Tests:

1000 iterations
A(1000); B(1000);
1 mil
A(1000000); B(1000000);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
1000 iterations
1 mil

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

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Let's dive into explaining the benchmark.

**What is being tested?**

The provided JSON represents two JavaScript microbenchmarks: `A` and `B`. Both functions are designed to perform a simple operation on an array of elements, but they use different methods to achieve this. The test case compares the performance of these two approaches:

1. **Map + Filter**: Function `A` uses the `map()` method to create a new array with transformed elements and then applies the `filter()` method to filter out every other element. This approach is typically more efficient because it avoids the overhead of creating an intermediate array.
2. **ForEach + If**: Function `B` uses the `forEach()` method to iterate over the array, and within each iteration, it checks if the index is even using an `if` statement. If the condition is true, it pushes a string element into an empty array.

**Options being compared**

The benchmark compares two versions of the same test case: one that uses Map + Filter (`A`) and another that uses ForEach + If (`B`). The number of iterations (1000 and 1 million) is also varied to assess performance under different conditions.

**Pros and Cons**

* **Map + Filter (Function A)**:
	+ Pros:
		- Typically more efficient because it avoids creating an intermediate array.
		- Can take advantage of optimizations in the JavaScript engine for `map()` and `filter()` methods.
	+ Cons:
		- Requires two function calls: one for `map()` and another for `filter()`.
		- May incur additional overhead due to the creation of a new array during the transformation process.
* **ForEach + If (Function B)**:
	+ Pros:
		- Simplified code with fewer function calls.
		- Can avoid the overhead of creating an intermediate array.
	+ Cons:
		- Typically less efficient because it involves more iterations and conditional checks.
		- May not take advantage of optimizations in the JavaScript engine for `forEach()`.

**Library used**

Neither Function A nor Function B relies on any external libraries. The operations are performed using native JavaScript features.

**Special JS feature or syntax**

There is no special JS feature or syntax explicitly mentioned in the benchmark definition. However, it's worth noting that some modern JavaScript engines and browsers may provide additional optimizations for specific array methods, such as `map()` and `forEach()`, which might affect the performance of these benchmarks.

**Other alternatives**

If you wanted to compare alternative approaches to these benchmarks, some possible options could be:

* Using a different data structure (e.g., using a Set instead of an Array)
* Implementing the operations manually without relying on built-in array methods
* Comparing the performance of other languages or platforms for running the same benchmark

Please note that each of these alternatives would require significant modifications to the benchmark definition and implementation.

Related benchmarks:

JS Map + filter vs ForEach (version: 0)

Benchmark to test map + filter vs Foreach if

Comparing performance of: 1000 iterations vs 1 mil

Created: 2 years ago by: Guest

Jump to the latest result

1000 iterations

1 mil

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):