Benchmark: For vs for of vs forEach

Script Preparation code:

var array = new Array(100000);

Tests:

for loop
let value; for (var i = 0; i < array.length; i++) { value = array[i]; }
forEach
let value; array.forEach(function(i) { value = i; });
for of
let value; for (var i of array) { value = i; }
reduce
const value = array.reduce((prev, current) => current, null)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for loop
forEach
for of
reduce

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/109.0.0.0 Safari/537.36

Browser/OS: Chrome 109 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
for loop	107.2 Ops/sec
forEach	5883.3 Ops/sec
for of	19767.9 Ops/sec
reduce	5381.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark definition and test cases.

**Benchmark Definition**

The benchmark measures the performance of three different loops in JavaScript: `for`, `for...of`, and `forEach`. The script preparation code creates an array of 100,000 elements. The benchmark is designed to test which loop executes faster.

**Options Compared**

The options being compared are:

* `for`: a traditional `for` loop that uses a counter variable (`i`) to iterate over the array.
* `for...of`: a newer `for` loop syntax that uses an iterator expression (`array[i]`) to iterate over the array.
* `forEach`: a method call on the array that iterates over its elements using a callback function.

**Pros and Cons**

1. **For Loop**
	* Pros: widely supported, easy to understand and implement.
	* Cons: can be slower than newer loop syntaxes due to the overhead of incrementing the counter variable.
2. **For...of Loop**
	* Pros: more concise and expressive, eliminates the need for explicit counter variables.
	* Cons: may have performance implications due to the use of iterator expressions.
3. **forEach Loop**
	* Pros: concise and easy to read, eliminates the need for explicit loops.
	* Cons: may not be as efficient as traditional `for` or `for...of` loops.

**Library and Purpose**

None of the test cases explicitly use a library or third-party function. The performance tests are designed to measure the native JavaScript engine's performance.

**Special JS Feature or Syntax**

There is no special JavaScript feature or syntax used in these benchmarks. All three loop options are standard features of the language.

**Alternative Loop Options**

Other alternative loop options that could be included in a benchmark like this include:

* `while`: a traditional `while` loop that iterates over the array.
* `map()`: a method call on the array that creates a new array with transformed elements.
* `filter()`: a method call on the array that creates a new array with filtered elements.

These alternative options could be included to provide a more comprehensive understanding of the performance characteristics of different JavaScript loops and iteration methods.

Related benchmarks:

For vs for of vs forEach (version: 0)

Comparing performance of: for loop vs forEach vs for of vs reduce

Created: one year ago by: Guest

Jump to the latest result

for loop

forEach

for of

reduce

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):