Benchmark: for vs for of2 - MeasureThat.net

Script Preparation code:

var count = 1000 * 1000
var data = [];

do {
  data.push(count);
} while(--count);

Tests:

for
let counter = 0; for (var index = 0; index < data.length; index++) { var obj = data[index]; if (obj == obj) counter++; } console.log(counter);
for of
let counter = 0; for (var obj of data) { if (obj == obj) counter++; } console.log(counter);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
for of

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):

LLMs can make mistakes. Check important info.

I'd be happy to explain the benchmark being tested.

**What is being tested?**

The provided JSON represents two individual test cases for measuring the performance difference between traditional `for` loops and a newer, more modern approach called "for...of" loops in JavaScript. The tests aim to determine which loop construct is faster when iterating over an array of values and incrementing a counter variable.

**Loop options compared**

There are two loop options being compared:

1. **Traditional `for` loop**: This type of loop uses a counter variable (`index`) that increments manually using the `++` operator. The loop iterates over the array, and for each iteration, it checks if an object is equal to itself.
2. **For...of loop**: This newer loop construct allows iterating directly over arrays and objects without the need for a manual counter. It uses the `for...of` syntax and an iterator object (`obj`) to access each element of the array.

**Pros and cons of each approach**

1. **Traditional `for` loop**:
	* Pros: More control over iteration, can be optimized manually for specific use cases.
	* Cons: Requires manual incrementing of the counter variable, which can lead to bugs if not done correctly.
2. **For...of loop**:
	* Pros: Simplifies iteration and reduces potential for errors, as it abstracts away manual counter management.
	* Cons: Can be slower due to additional overhead introduced by the iterator object.

**Library usage**

There is no explicit library mentioned in the provided JSON. However, if we consider the `data` array being iterated over, we can assume that a built-in JavaScript feature (or a standard library) is used for creating and manipulating arrays.

**Special JavaScript features or syntax**

The test case uses the "for...of" loop, which is a newer JavaScript feature introduced in ECMAScript 2015. This feature allows iterating directly over arrays and objects without the need for manual counter management.

**Other alternatives**

There are alternative ways to iterate over arrays in JavaScript, such as:

1. **Using `forEach()`**: While not directly comparable to traditional loops or for...of loops, `forEach()` is a built-in method that can be used to iterate over arrays.
2. **Using `map()`, `filter()`, and other array methods**: These methods are designed for more functional programming-style approaches and may have different performance characteristics compared to traditional loops.

In summary, the provided benchmark aims to determine which loop construct (traditional `for` or for...of) is faster when iterating over an array of values. The results will provide insights into the performance differences between these two approaches in modern JavaScript environments.

Latest run results:

Run details: (Test run date: 11 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:122.0) Gecko/20100101 Firefox/122.0

Browser/OS: Firefox 122 on Windows

View result in a separate tab

Test name	Executions per second
for	587.2 Ops/sec
for of	165.2 Ops/sec

Related benchmarks:

for vs for of2 (version: 0)

Comparing performance of: for vs for of

Created: 11 months ago by: Guest

Jump to the latest result

for

for of

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):