Benchmark: for vs foreach ej

Script Preparation code:

function generateTestArray() {
  const result = [];
  for (let i = 0; i < 1000000; ++i) {
    result.push({
      a: i,
      b: i / 2,
      r: 0,
    });
  }
  return result;
}

Tests:

.forEach
const array = generateTestArray(); array.forEach((x) => { x.r = x.a + x.b; });
for
const array = generateTestArray(); for(let index = 0; index < array.length; index++) { array[index].r = array[index].a + array[index].b; }
for name first
const array = generateTestArray(); for(let index = 0; index < array.length; index++) { const value = array[index] value.r = value.a + value.b; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
.forEach
for
for name first

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and its test cases.

**Benchmark Definition Json:**

The provided JSON defines a JavaScript microbenchmark that measures the performance of two different approaches to iterate over an array:

1. `for` loop
2. `.forEach()` method

In the `Script Preparation Code`, we see a function `generateTestArray()` that generates a large array with 1 million elements, each containing three properties: `a`, `b`, and `r`. The `generateTestArray()` function is used to create an array for testing.

**Individual Test Cases:**

There are three test cases:

1. `.forEach()`: This test case uses the `.forEach()` method to iterate over the generated array, updating each element's property `r` with the sum of its properties `a` and `b`.
2. `for`: This test case uses a traditional `for` loop to iterate over the generated array, also updating each element's property `r` with the sum of its properties `a` and `b`. However, this test case has an additional difference: it uses variable interpolation (`const value = array[index]`) instead of directly accessing the array elements.
3. `for name first`: This test case is similar to the `for` loop test case, but with another minor difference: it also uses variable interpolation (`const value = array[index]`) instead of direct array access.

**Options Comparison:**

The two main options being compared are:

1. `.forEach()` method
2. Traditional `for` loop

**Pros and Cons:**

* `.forEach()` method:
	+ Pros:
		- Easier to read and maintain, as it abstracts away the iteration logic.
		- Can be more concise and expressive, especially when working with callbacks.
	+ Cons:
		- May have additional overhead due to the callback mechanism, which can introduce performance penalties.
		- Limited control over iteration variables and loop conditions.
* Traditional `for` loop:
	+ Pros:
		- More traditional and familiar syntax for many developers.
		- Offers more control over iteration variables and loop conditions.
		- Can be optimized for specific use cases (e.g., using incremental indices).
	+ Cons:
		- Requires explicit handling of loop logic, which can make the code harder to read and maintain.

**Library:**

There is no explicit library mentioned in the provided benchmark definition or test cases. However, some browsers might have internal optimizations or features that could influence the performance results (e.g., V8 engine's optimization for `forEach()`).

**Special JS Feature/Syntax:**

Variable interpolation (`const value = array[index]`) is used in two of the test cases (`for` and `for name first`). This feature allows dynamic referencing to array elements, but its impact on performance may vary depending on the specific JavaScript engine and browser implementation.

**Other Alternatives:**

Other iteration methods that could be considered for benchmarking include:

1. `for...of`: A more modern and concise iteration method introduced in ECMAScript 2017.
2. Array.prototype.map(): A method that creates a new array with transformed elements, which can be useful for certain use cases.
3. Recursive functions: For iterative arrays or data structures that don't fit into the traditional loop or `forEach()` pattern.

Keep in mind that the choice of iteration method often depends on the specific problem requirements and personal preference.

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/114.0.0.0 Safari/537.36

Browser/OS: Chrome 114 on Windows

View result in a separate tab

Test name	Executions per second
.forEach	14.3 Ops/sec
for	21.2 Ops/sec
for name first	21.0 Ops/sec

Related benchmarks:

for vs foreach ej (version: 0)

Comparing performance of: .forEach vs for vs for name first

Created: one year ago by: Guest

Jump to the latest result

.forEach

for

for name first

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):