Benchmark: for..of - MeasureThat.net

Script Preparation code:

var arr = new Array(10000).map(()=>Math.random())

Tests:

0
var sum=''; for(const item of arr){ sum+=item; }
1
var sum=''; for(let i=0; i<arr.length; i++){ sum+=arr[i]; }
2
var sum=''; for(let i=0, len=arr.length; i<len; i++){ sum+=arr[i]; }
3 + get link
var sum=''; let arrs = arr; for(let i=0, len=arrs.length; i<len; i++){ sum+=arrs[i]; }
4 + get link
var sum=''; let arrs = arr; for(const item of arrs){ sum+=item; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
0
1
2
3 + get link
4 + get link

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):

LLMs can make mistakes. Check important info.

The provided JSON represents a benchmark test for the `for..of` loop in JavaScript. The goal of this test is to compare the performance of different variations of the `for..of` loop.

**Benchmark Definition**

In the "Benchmark Definition" section, we have four different versions of the `for..of` loop:

1. `for (const item of arr) { sum += item; }`
2. `for (let i = 0; i < arr.length; i++) { sum += arr[i]; }`
3. `for (let i = 0, len = arr.length; i < len; i++) { sum += arr[i]; }`
4. `let arrs = arr; for (const item of arrs) { sum += item; }`

**Options Compared**

The test compares the performance of these four different versions of the `for..of` loop:

* **Version 1**: Uses the `for...of` loop with a const declaration, which allows it to iterate over an array without a fixed index.
* **Version 2**: Uses the traditional `for` loop with a let declaration and indexing into the array using square brackets (`arr[i]`).
* **Version 3**: Uses the traditional `for` loop with a let declaration and a separate variable for the array length (`len = arr.length; i < len; i++`).
* **Version 4**: Assigns the array to a new variable (`let arrs = arr`) before using it in the `for...of` loop.

**Pros and Cons**

Here are some pros and cons of each approach:

1. **Version 1**:
	* Pros: More concise and expressive code, avoids indexing into the array.
	* Cons: May not be as readable for those unfamiliar with `for...of`.
2. **Version 2**:
	* Pros: Widely supported and well-known syntax, easy to read and write.
	* Cons: Requires indexing into the array, which can lead to off-by-one errors.
3. **Version 3**:
	* Pros: Avoids the need for indexing into the array, but requires an extra variable for the length.
	* Cons: May be less readable due to the additional variable, and is less common than other approaches.
4. **Version 4**:
	* Pros: Similar to Version 1, but with a temporary assignment for better readability.
	* Cons: Requires assigning the array to a new variable, which can lead to unnecessary memory allocation.

**Library Use**

There are no libraries used in this benchmark test.

**Special JS Features or Syntax**

The `for...of` loop is a built-in JavaScript feature that allows iterating over arrays and other iterable objects without a fixed index. It was introduced in ECMAScript 2015 (ES6).

**Other Alternatives**

If you're looking for alternatives to the `for...of` loop, you can consider:

* **Traditional `for` loop**: As shown in Version 2.
* **Array methods**: Such as `map()`, `forEach()`, or `reduce()`, which can simplify iteration over arrays but may not be suitable for all use cases.

In summary, the test compares four different variations of the `for...of` loop in JavaScript, each with its pros and cons. The choice of approach depends on the specific use case and personal preference.

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.75 Safari/537.36

Browser/OS: Chrome 86 on Windows

View result in a separate tab

Test name	Executions per second
0	9783.9 Ops/sec
1	468.1 Ops/sec
2	891.6 Ops/sec
3 + get link	10675.9 Ops/sec
4 + get link	9761.5 Ops/sec

Related benchmarks:

for..of (version: 0)

Comparing performance of: 0 vs 1 vs 2 vs 3 + get link vs 4 + get link

Created: 4 years ago by: Registered User

Jump to the latest result

0

1

2

3 + get link

4 + get link

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):