Benchmark: for vs forEach vs for-of vs for-reverse

Script Preparation code:

var array = new Array(100);

Tests:

for
for (var i = 0; i < array.length; i++) { array[i]; }
forEach
array.forEach(function(item, index) { return item; });
for-of
for (var item of array) { item; }
for-reverse
for (var i = array.length; i--;) { array[i]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
forEach
for-of
for-reverse

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):

LLMs can make mistakes. Check important info.

**What is tested on the provided JSON?**

The provided JSON represents a JavaScript microbenchmark, specifically comparing four different loop constructs: `for`, `forEach`, `for-of`, and `for-reverse`. The benchmark tests which approach executes the most iterations per second.

**Options compared:**

1. **`for`**: A traditional loop construct using a counter variable.
2. **`forEach`**: A method on arrays that allows iterating over each element with an optional callback function.
3. **`for-of`**: A newer loop construct introduced in ECMAScript 2015, which uses the `of` keyword to iterate over array elements.
4. **`for-reverse`**: An optimized version of the traditional `for` loop that iterates in reverse order.

**Pros and Cons:**

1. **`for`**:
	* Pros: Widely supported, easy to understand, and well-documented.
	* Cons: Can be less efficient than other options due to the overhead of incrementing the counter variable.
2. **`forEach`**:
	* Pros: Convenient for iterating over arrays with a callback function.
	* Cons: May not perform as well as `for` or `for-of`, especially for large datasets, since it involves creating an additional stack frame for each iteration.
3. **`for-of`**:
	* Pros: Efficient and concise way to iterate over array elements.
	* Cons: Requires ECMAScript 2015 support and may not be as well-known as other options.
4. **`for-reverse`**:
	* Pros: Optimized for reverse iteration, potentially reducing overhead.
	* Cons: Less intuitive than traditional `for` loops and may require additional understanding.

**Library/Utilities used:**

None mentioned in the provided JSON.

**Special JavaScript features or syntax:**

The benchmark uses ECMAScript 2015's `for-of` loop construct (`var item of array`) and the `forEach` method on arrays. The traditional `for` loop also relies on a counter variable.

**Other considerations:**

* The benchmark assumes that the input array has at least one element.
* The results may vary depending on the specific use case, hardware, and JavaScript engine used.

**Alternatives:**

1. **`while` loops**: An alternative to traditional `for` loops for more control over iteration.
2. **Array.prototype.map()`: A method that creates a new array with transformed elements, which can be compared to `forEach`.
3. **Async/await loops**: For asynchronous iterations or when working with promises.

Keep in mind that this benchmark is designed to compare specific loop constructs and may not be representative of all use cases or scenarios.

Related benchmarks:

for vs forEach vs for-of vs for-reverse (version: 0)

for vs forEach vs for-of vs for-reverse

Comparing performance of: for vs forEach vs for-of vs for-reverse

Created: 4 years ago by: Guest

Jump to the latest result

for

forEach

for-of

for-reverse

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):