Benchmark: array foreach vs loop

Script Preparation code:

var arr = ['A', 'B', 'C', 'D', 'E'];
var newValue = "T";

Tests:

Foreach
arr.forEach((value) => { newValue += value; });
Loop
for (const value of arr) { newValue += value; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Foreach
Loop

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/96.0.4664.110 Safari/537.36

Browser/OS: Chrome 96 on Windows

View result in a separate tab

Test name	Executions per second
Foreach	1197757.9 Ops/sec
Loop	1000366.1 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested.

**Benchmark Description**

The benchmark is comparing two approaches to iterate over an array: `forEach` (foreach loop) and traditional `for` loop with a `const value of arr` syntax. The goal is to measure which approach is faster in JavaScript.

**Options Compared**

Two options are compared:

1. **Foreach**: Uses the `Array.prototype.forEach()` method, which calls a callback function for each element in the array.
2. **Loop**: Uses a traditional `for` loop with a `const value of arr` syntax, which iterates over the array using a `for...of` loop.

**Pros and Cons**

**Foreach:**

Pros:

* Easier to write, especially for simple iterations
* Less error-prone, as the callback function is defined separately

Cons:

* May incur additional overhead due to the method call and checking if the length of the array is 0
* May be slower due to JavaScript's internal caching mechanisms

**Loop:**

Pros:

* Typically faster, as it avoids the overhead of the `forEach()` method
* More control over iteration and can handle edge cases better

Cons:

* Can be more error-prone, especially for complex iterations
* Requires a separate variable to store the array length, which can lead to issues if not handled correctly

**Library/Utility**

The `newValue` variable is used to accumulate values from the array. This suggests that it's a utility or placeholder value, and the actual calculation is being performed on the `value` variables within the callback function or loop.

**Special JavaScript Feature/Syntax**

The test uses the **const value of arr** syntax, which was introduced in ECMAScript 2015 (ES6). This feature allows for more expressive and concise code by providing a way to iterate over arrays without having to declare an explicit variable. The use of `for...of` loops also makes the code more readable and easier to maintain.

**Other Alternatives**

Other alternatives for iterating over arrays in JavaScript include:

* Using `Array.prototype.map()` or `Array.prototype.filter()`, which can be slower but offer more functionality
* Implementing a custom iterator using `Symbol.iterator` or `Array.prototype[Symbol.iterator]`
* Using a library like Lodash, which provides utility functions for array manipulation

Keep in mind that the choice of iteration method depends on the specific use case and performance requirements.

**Benchmark Results**

The provided benchmark results show the execution time per second for each test case. The "Foreach" test has a slightly higher execution time than the "Loop" test, indicating that traditional `for` loops might be faster in this scenario. However, it's essential to note that these results are specific to this particular benchmark and may not generalize across all use cases or JavaScript environments.

Please let me know if you'd like more information on any of these points!

Related benchmarks:

array foreach vs loop (version: 0)

Comparing performance of: Foreach vs Loop

Created: 3 years ago by: Registered User

Jump to the latest result

Foreach

Loop

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):