Benchmark: set for-of vs iterator

Script Preparation code:

var arr = [];
while(arr.length < 1000) arr.push(Math.random()*100000);
var set = new Set(arr);

Tests:

for of
for(v of set) { let a = v / 2; }
iter
let iter = set.values(); let item = iter.next(); while(!item.done){ let a = item.value / 2; item = iter.next(); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for of
iter

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/126.0.0.0 Safari/537.36

Browser/OS: Chrome 126 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
for of	14632.8 Ops/sec
iter	426408.2 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark compares two approaches to iterate over a Set object: using a traditional for loop with the `of` keyword (also known as "for-of") versus using an iterator manually. The test creates a large array, converts it to a Set, and then iterates over the set using both methods.

**Options Compared**

The benchmark compares two options:

1. **For-Of Loop**: Uses the `of` keyword to iterate over the Set object in a traditional for loop syntax.
2. **Manual Iterator**: Manually creates an iterator from the Set object and uses its `next()` method to retrieve each value.

**Pros and Cons**

**For-Of Loop:**

Pros:

* Readability: The code is easier to read and understand, as it follows a more conventional for loop structure.
* Syntax Sugar: The `of` keyword provides a concise way to iterate over a Set object without manually creating an iterator.

Cons:

* Performance Overhead: Some argue that the `for-of` loop can introduce performance overhead due to the need to call the array's `length` property and create an iterator internally.

**Manual Iterator:**

Pros:

* Control: By manually creating an iterator, you have more control over the iteration process and can optimize it for specific use cases.
* Performance: In some cases, manual iteration can be faster than using the `for-of` loop, as it avoids the overhead of creating an iterator internally.

Cons:

* Complexity: The code requires more lines to manually create and manage the iterator, making it less readable.

**Other Considerations**

The benchmark assumes that the Set object has a large number of elements (1000 in this case), which may not be representative of real-world scenarios where sets are typically smaller. Additionally, the benchmark focuses on raw performance numbers rather than more nuanced aspects like memory usage or cache efficiency.

**Library Usage**

In this benchmark, the `Set` object is used as is, without any external libraries. The Set data structure is a built-in JavaScript object that provides efficient membership testing and iteration capabilities.

**Special JS Features/Syntax**

The benchmark uses the following special features/syntax:

* The `of` keyword in the for loop syntax.
* The `values()` method to create an iterator from the Set object.
* The `next()` method to retrieve each value from the iterator.
* The use of a while loop with manual iteration.

Note that these features are widely supported and don't require any special knowledge or configuration.

Related benchmarks:

set for-of vs iterator (version: 0)

Comparing performance of: for of vs iter

Created: 8 years ago by: Guest

Jump to the latest result

for of

iter

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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