Benchmark: ForOf vs Foreach vs map

Script Preparation code:

var arr = [];
for (var i = 0; i < 1000; i++) {
  arr[i] = i;
}

function someFn(i) {
  return i * 3 * 8;
}

Tests:

foreach
arr.forEach((item) => { someFn(item); })
ForOf
for (const item of arr) { someFn(item); }
map
arr.map(item => someFn(item))

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
foreach
ForOf
map

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.

Let's break down the provided benchmark and its results.

**What is being tested?**

The benchmark measures the performance of three different approaches to iterate over an array in JavaScript:

1. `forEach`: A callback-based iteration method where each element of the array is executed once.
2. `ForOf`: A new, more modern way of iterating over arrays introduced in ECMAScript 2015 (ES6). It uses a loop that only includes elements from the array for which an entry is defined.
3. `map()`: A method that creates a new array with the results of applying a provided function to each element of the original array.

**Options compared**

The three options are being compared in terms of their execution speed (measured by `ExecutionsPerSecond`). The benchmark aims to determine which approach is fastest for this specific use case.

**Pros and Cons of each approach:**

1. **`forEach`**:
	* Pros: Simple, widely supported, and easy to implement.
	* Cons: Does not provide any iteration limit or cancellation mechanism.
2. **`ForOf`**:
	* Pros: More efficient than `forEach`, as it avoids the overhead of a callback function.
	* Cons: Requires ECMAScript 2015 (ES6) support, which might not be available in older browsers.
3. **`map()`**:
	* Pros: Creates a new array with transformed elements, which can simplify code and improve readability.
	* Cons: May incur higher overhead than `forEach` due to the creation of a new array.

**Library used (if any)**

In this benchmark, no external library is explicitly mentioned. However, it's worth noting that some JavaScript engines may use internal libraries or optimizations that might affect the results.

**Special JS feature or syntax**

The test case uses ES6 features:

* `ForOf`: A new iteration method introduced in ECMAScript 2015 (ES6).
* `map()`: Also introduced in ECMAScript 2015 (ES6).

These features are widely supported in modern browsers, including Chrome 100.

**Other alternatives**

While not explicitly mentioned in the benchmark, other approaches to iterating over arrays might be considered:

* `while` loop with an index variable
* Using `Array.prototype.every()` or `Array.prototype.some()`
* Using a custom implementation of iteration using bitwise operations (e.g., `for (var i = 0; ; i++)`)

However, these alternatives are not being tested in this benchmark.

In summary, the benchmark measures the performance of three different approaches to iterate over an array in JavaScript: `forEach`, `ForOf`, and `map()`. The results will help determine which approach is fastest for this specific use case.

Related benchmarks:

ForOf vs Foreach vs map (version: 0)

Comparing performance of: foreach vs ForOf vs map

Created: 4 years ago by: Guest

Jump to the latest result

foreach

ForOf

map

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):