Benchmark: ES6 forEach vs native for loop

Script Preparation code:

var values = [{a: 30310}, {b: 100303}, {c: 3040494}]

Tests:

ES6 forEach
var count = 0; values.forEach((v,i) => { if (v.a != null) { count++; } })
Native for loop
var count = 0; for (var i = 0; i < values.length; i++) { if (values[i].a != null) { count++; } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
ES6 forEach
Native for loop

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

Let's dive into the provided benchmark and break down what is being tested, compared, and their pros and cons.

**What is being tested?**

The provided benchmark compares two approaches to iterate over an array: ES6 `forEach` and native for loop. The test case uses a predefined JavaScript array `values` with three elements.

**Options being compared:**

1. **ES6 `forEach`:**
	* Purpose: To execute a callback function once for each element in the array.
	* Syntax: `array.forEach(callbackFunction)`.
2. **Native For Loop:**
	* Purpose: To iterate over an array using a traditional loop structure.
	* Syntax: `for (var i = 0; i < array.length; i++) { ... }`.

**Pros and Cons of each approach:**

1. **ES6 `forEach`:**
	* Pros:
		+ Concise and expressive syntax.
		+ No need to keep track of indices or loop counters manually.
		+ Built-in support for iterating over arrays in modern browsers.
	* Cons:
		+ May have slower performance compared to native for loops due to the overhead of JavaScript's built-in functions.
		+ May not be optimized for performance by all JavaScript engines.
2. **Native For Loop:**
	* Pros:
		+ Often faster and more efficient than `forEach` due to direct access to array elements.
		+ Can be more predictable and easier to debug in certain cases.
	* Cons:
		+ Requires manual management of indices and loop counters, which can lead to errors.
		+ Less concise and less expressive syntax compared to `forEach`.

**Library usage:**

There is no explicit library mentioned in the benchmark. However, it's worth noting that some JavaScript engines or browsers may have optimizations or features that affect performance, such as:

* V8 (used by Chrome): Has its own optimizer and compiler for JavaScript code.
* SpiderMonkey (used by Firefox): Has a Just-In-Time (JIT) compiler for improved performance.

**Special JS feature or syntax:**

There are no special JavaScript features or syntax mentioned in the benchmark. However, if we were to extend this comparison to other approaches, some notable alternatives include:

* `Array.prototype.forEach.call()`: A more explicit way of calling `forEach` on an array.
* `Map.prototype.forEach()`: Similar to `forEach` but designed for use with Maps (key-value pairs).
* `for...of` loop: A newer looping construct that's similar to `forEach` but can be used in different contexts.

**Other alternatives:**

Some other approaches that could be compared include:

* Using `reduce()` instead of `forEach`: This might lead to slightly different performance characteristics due to the nature of these functions.
* Implementing a custom iterator or generator function: These approaches would provide more control over iteration but often at the cost of readability and conciseness.

In conclusion, the provided benchmark compares two common approaches to iterate over arrays in JavaScript: ES6 `forEach` and native for loops. The choice between these approaches depends on factors such as performance requirements, code readability, and personal preference.

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/103.0.0.0 Safari/537.36

Browser/OS: Chrome 103 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
ES6 forEach	10885547.0 Ops/sec
Native for loop	2240797.0 Ops/sec

Related benchmarks:

ES6 forEach vs native for loop (version: 0)

Comparing performance of: ES6 forEach vs Native for loop

Created: 4 years ago by: Guest

Jump to the latest result

ES6 forEach

Native for loop

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):