Benchmark: for vs foreach vs some

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; });
some
for (var i = -1, l = array.length; ++i > l;) { array[i]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
foreach
some

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Measuring the performance of different loop constructs in JavaScript is a fascinating topic.

**Loop Constructs**

The benchmark compares three types of loops:

1. **Traditional `for` loop**: This is a classic loop construct that uses an incrementing variable (`i`) to iterate over an array.
2. **`forEach` loop**: Introduced in ECMAScript 5, this loop construct uses the `Array.prototype.forEach()` method to iterate over an array. It's designed to be more concise and expressive than traditional `for` loops.
3. **`some` loop**: This is a less common loop construct that uses a conditional statement (`while (i < array.length)`) to iterate over an array. The loop continues as long as the condition is true.

**Options Compared**

The benchmark compares these three loop constructs against each other in terms of performance. Each test case runs the corresponding loop construct on the same input data (an array of 100 elements).

**Pros and Cons**

Here's a brief summary of the pros and cons of each loop construct:

* **Traditional `for` loop**: Pros:
	+ Easy to understand and implement.
	+ Can be optimized for performance by using incrementing variables carefully.
Cons:
	+ Less concise than other options.
	+ May require more memory allocation and deallocation.
* **`forEach` loop**: Pros:
	+ Concise and expressive syntax.
	+ Designed for modern JavaScript development.
Cons:
	+ May incur additional overhead due to the `Array.prototype.forEach()` method call.
	+ Limited control over iteration variables.
* **`some` loop**: Pros:
	+ Can be optimized for performance by avoiding unnecessary iterations.
Cons:
	+ Less intuitive and less widely supported than other options.
	+ Requires manual memory management.

**Library: Array.prototype.forEach()**

The `Array.prototype.forEach()` method is a built-in JavaScript function that allows iterating over an array. Its purpose is to execute a callback function for each element in the array, without requiring a traditional loop construct.

In the benchmark, the `forEach` loop uses this method to iterate over the array. The callback function simply returns the current item, which serves as a proxy value.

**Special JS Feature: Arrow Functions**

The `forEach` loop also employs arrow functions (`() => { ... }`) to define the callback function. This is a modern JavaScript feature introduced in ECMAScript 2015 (ES6).

Arrow functions are concise and expressive syntax for defining small, single-expression functions. They're widely supported by modern browsers and can improve code readability.

However, it's worth noting that arrow functions may incur additional overhead due to their syntax. In this benchmark, the performance difference between using an arrow function or a traditional function declaration is negligible.

**Other Alternatives**

If you want to explore alternative loop constructs in JavaScript, here are some options:

* **`for...in` loop**: Iterate over an array's properties (index and value) using the `for...in` loop construct.
* **`reduce()` method**: Use the `Array.prototype.reduce()` method to reduce an array to a single value by applying a cumulative operation.
* **Custom loops**: Implement your own custom loop constructs using JavaScript's native functions, such as `while`, `do...while`, or even recursive functions.

Latest run results:

Run details: (Test run date: 6 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.117 Safari/537.36

Browser/OS: Chrome 66 on Mac OS X 10.13.4

View result in a separate tab

Test name	Executions per second
for	66967.0 Ops/sec
foreach	3270692.2 Ops/sec
some	14128206.0 Ops/sec

Related benchmarks:

for vs foreach vs some (version: 0)

Compare loop performance

Comparing performance of: for vs foreach vs some

Created: 6 years ago by: Guest

Jump to the latest result

for

foreach

some

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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