Benchmark: for vs foreach vs for..of (z)

Script Preparation code:

var array = [];
for (let i = 0; i < 10000000; i++) {
    array.push(i);
}

var object = {};

Tests:

for
for (let i = 0; i < array.length; i++) { object[i] = true; }
foreach
array.forEach((i) => { object[i] = true; });
for..of
for (const i of array) { object[i] = true; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
foreach
for..of

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks!

**Benchmark Definition**

The provided JSON represents a benchmark definition for measuring the performance of three different loop constructs in JavaScript: `for`, `forEach`, and `for..of`. The script preparation code creates an empty array and object, which are used as inputs for the loops.

Here's a brief explanation of each test case:

1. **`for`**: This loop uses a traditional `for` loop with an index variable `i` that increments from 0 to `array.length - 1`. The loop pushes values into the `object` using the index.
2. **`forEach`**: This loop uses the `forEach` method, which calls a provided callback function for each element in the array. In this case, the callback function simply sets the value of `object[i]` to `true`, where `i` is the current array index.
3. **`for..of`**: This loop uses a newer `for...of` loop construct, which iterates over the elements of an array using an iterator object. In this case, the loop sets the value of `object[i]` to `true`, where `i` is the current array element.

**Options Compared**

The benchmark compares the performance of these three loop constructs:

* **Pros and Cons:**
	+ `for`: This is a traditional loop construct that provides fine-grained control over indexing. However, it can be verbose and may lead to off-by-one errors.
	+ `forEach`: This loop is more concise and easier to read than the `for` loop. However, it may not provide direct access to the index variable.
	+ `for...of`: This loop provides a convenient way to iterate over arrays without manual indexing. However, it may have performance overhead compared to traditional loops.
* **Other Considerations:**
	+ Loop iterations can be affected by factors like array size, JavaScript engine optimizations, and platform-specific nuances.

**Library and Special JS Features**

The benchmark does not explicitly use any libraries or special JavaScript features beyond the standard `Array` and `Object` classes. However, it's worth noting that the `forEach` loop uses a callback function, which is a common pattern in JavaScript.

**Benchmark Results**

The latest benchmark results show the performance of each loop construct:

* **`for`**: 85.72223663330078 executions per second
* **`for..of`**: 16.487634658813477 executions per second
* **`forEach`**: 12.495660781860352 executions per second

These results indicate that the `for` loop is the fastest, followed by the `for...of` loop, and then the `forEach` loop.

**Alternatives**

Other alternatives for loop constructs in JavaScript include:

* **`while` loops**: These provide more control over indexing but can be less readable than other options.
* **`map()` and `reduce()` methods**: These are functional programming constructs that can simplify certain types of looping, but may have performance overhead compared to traditional loops.
* **Iterators and generators**: These provide a more efficient way to iterate over arrays and objects, but require a deeper understanding of JavaScript's iterative model.

I hope this explanation helps you understand the benchmark definition and its underlying mechanics!

Related benchmarks:

for vs foreach vs for..of (z) (version: 0)

Compare loop performance

Comparing performance of: for vs foreach vs for..of

Created: 3 years ago by: Guest

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for

foreach

for..of

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):