Benchmark: Iterator vs Index for loop (global sum)

Script Preparation code:

var arr = [];
for(let i = 0; i < 10000; i++) {
  arr.push(Math.random());
}
var arrLength = arr.length;
var sum = 0;

AخA
 
var arr = [];for(let i = 0; i < 10000; i++) {  arr.push(Math.random());}var arrLength = arr.length;var sum = 0;

Tests:

Iterator for loop
for(const num of arr) { sum += num; }
for(const num of arr) {
sum += num;
}
Index for loop
for(let i = 0; i < arrLength; i++) { sum += arr[i]; }
for(let i = 0; i < arrLength; i++) {
sum += arr[i];
}

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Experimental features:

Memory measurements supported only in Chrome.
For precise memory measurements Chrome must be launched with --enable-precise-memory-info flag.
More information: Monitoring JavaScript Memory

Test case name	Result
Iterator for loop
Index for loop

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/110.0

Browser/OS: Firefox 110 on Linux

View result in a separate tab

Test name	Executions per second
Iterator for loop	5218.8 Ops/sec
Index for loop	6839.0 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 7 months ago):

Let's dive into the world of JavaScript microbenchmarks and explore what's being tested in this particular benchmark.

What is being tested?

The provided JSON represents two individual test cases that compare the performance of different approaches to iterate over an array in JavaScript:

Iterator for loop: This approach uses a for...of loop, which creates an iterator object from the array and allows it to be iterated over without exposing its underlying implementation.
Index for loop: This approach uses a traditional for loop with an index variable (i) to iterate over the array.

Options compared

The two approaches are being compared in terms of their performance, measured by the number of executions per second.

Pros and Cons:

Iterator for loop
- Pros:
  - Can be more memory-efficient since it doesn't require creating a separate index variable.
  - Can be faster due to reduced overhead from indexing operations.
- Cons:
  - May have slower startup times due to the creation of the iterator object.
Index for loop
- Pros:
  - Typically has better cache locality, which can lead to faster performance.
  - Often has better support for concurrent execution and parallelization.
- Cons:
  - Can be less memory-efficient since it requires creating a separate index variable.
  - May have slower performance due to indexing operations.

Library usage

There is no explicit library used in this benchmark, but the for...of loop syntax relies on the JavaScript iterator API, which is part of the ECMAScript standard.

Special JS feature or syntax

The test case uses the for...of loop syntax, which is a relatively recent addition to the JavaScript language (introduced in ECMAScript 2015). This syntax allows for more concise and expressive iteration over arrays and other iterable objects.

Other alternatives

If you're interested in exploring alternative approaches, here are a few options:

Array.prototype.forEach(): A method that iterates over an array and executes a provided callback function for each element.
Array.prototype.map(): A method that creates a new array by applying a provided callback function to each element of the original array.
Array.prototype.reduce(): A method that applies a reduction operation to each element of the array, using a provided callback function.

Keep in mind that these alternatives may not be as performant or memory-efficient as the for...of loop syntax used in this benchmark.

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks and explore what's being tested in this particular benchmark.

**What is being tested?**

The provided JSON represents two individual test cases that compare the performance of different approaches to iterate over an array in JavaScript:

1. **Iterator for loop**: This approach uses a `for...of` loop, which creates an iterator object from the array and allows it to be iterated over without exposing its underlying implementation.
2. **Index for loop**: This approach uses a traditional `for` loop with an index variable (`i`) to iterate over the array.

**Options compared**

The two approaches are being compared in terms of their performance, measured by the number of executions per second.

**Pros and Cons:**

1. **Iterator for loop**
	* Pros:
		+ Can be more memory-efficient since it doesn't require creating a separate index variable.
		+ Can be faster due to reduced overhead from indexing operations.
	* Cons:
		+ May have slower startup times due to the creation of the iterator object.
2. **Index for loop**
	* Pros:
		+ Typically has better cache locality, which can lead to faster performance.
		+ Often has better support for concurrent execution and parallelization.
	* Cons:
		+ Can be less memory-efficient since it requires creating a separate index variable.
		+ May have slower performance due to indexing operations.

**Library usage**

There is no explicit library used in this benchmark, but the `for...of` loop syntax relies on the JavaScript iterator API, which is part of the ECMAScript standard.

**Special JS feature or syntax**

The test case uses the `for...of` loop syntax, which is a relatively recent addition to the JavaScript language (introduced in ECMAScript 2015). This syntax allows for more concise and expressive iteration over arrays and other iterable objects.

**Other alternatives**

If you're interested in exploring alternative approaches, here are a few options:

1. **Array.prototype.forEach()**: A method that iterates over an array and executes a provided callback function for each element.
2. **Array.prototype.map()**: A method that creates a new array by applying a provided callback function to each element of the original array.
3. **Array.prototype.reduce()**: A method that applies a reduction operation to each element of the array, using a provided callback function.

Keep in mind that these alternatives may not be as performant or memory-efficient as the `for...of` loop syntax used in this benchmark.

Related benchmarks:

Iterator vs Index for loop (global sum) (version: 0)

Comparing performance of: Iterator for loop vs Index for loop

Created: 2 years ago by: Registered User

Jump to the latest result

Iterator for loop

Index for loop

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 7 months ago):