Benchmark: for vs forEach vs for-of

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; }

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:

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/94.0.4606.81 Safari/537.36 OPR/80.0.4170.91

Browser/OS: Opera 80 on Windows

View result in a separate tab

Test name	Executions per second
for	91283.3 Ops/sec
forEach	5583785.5 Ops/sec
for-of	9633448.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks!

**What is tested?**

The provided JSON represents a benchmark test that compares the performance of three different looping constructs in JavaScript:

1. `for` loop
2. `.forEach()` method
3. `for-of` loop

These loops are used to iterate over an array and perform some operation on each element.

**Options compared:**

*   The three options being compared are:
    *   `for` loop with a traditional loop variable (`i`)
    *   `.forEach()` method, which is a built-in JavaScript array method
    *   `for-of` loop, also known as the "iterator" or "iteration" loop

**Pros and cons of each approach:**

*   **For loop:** This is a traditional looping construct in JavaScript. The pros include:
    *   Good performance, especially for small arrays, since it avoids the overhead of function calls
    *   Easy to read and understand
*   **ForEach() method:** This is a built-in JavaScript array method that iterates over an array using a callback function. The pros include:
    *   High-level abstraction, making it easy to write generic code
    *   Supports various callback functions (e.g., arrow functions)
*   **For-of loop:** This is a relatively new looping construct in JavaScript introduced in ECMAScript 2015. The pros include:
    *   Concise syntax, making it easier to read and understand
    *   Less memory overhead compared to traditional `for` loops

However, the cons of each approach are:

*   **For loop:** It requires manual index management, which can be error-prone.
*   **ForEach() method:** It can lead to performance issues for very large arrays due to function call overhead and garbage collection.
*   **For-of loop:** It's a relatively new feature, so some older browsers might not support it.

**Other considerations:**

*   The benchmarking results are specific to the Opera 80 browser on Windows Desktop, which may not be representative of all users' environments.
*   The `array` variable is initialized with 100 elements, but in practice, this value could vary depending on the test scenario.

**Library and special JS features:**

There are no libraries mentioned in the provided JSON. However, if you were to use the `.forEach()` method, it utilizes the built-in `Array.prototype.forEach()`, which is a part of the JavaScript standard library.

**Other alternatives:**

If you wanted to explore other looping constructs or alternative methods for array iteration, some examples include:

*   **While loop:** A traditional looping construct that can be used for array iteration.
*   **Reduce() method:** An array method that reduces an array to a single value using a callback function.
*   **Map() and filter() methods:** Array methods that transform arrays by applying a callback function or filtering elements.

Keep in mind that each alternative has its own pros and cons, depending on the specific use case.

Related benchmarks:

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

for vs forEach vs for-of

Comparing performance of: for vs forEach vs for-of

Created: 5 years ago by: Guest

Jump to the latest result

for

forEach

for-of

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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