Benchmark: rest parameters vs arguments (no extra args)

Script Preparation code:

window.els = [];

function t1() {
  window.els.push(...arguments);
}

function t2(...args) {
  window.els.push(...args);
}

Tests:

arguments
window.els.length = 0; for (let i = 0; i < 2000; i++) { if (i % 3 === 0) { els.push(t1('div', {class: 'foo'}, i, i + 1, i + 2)); } else { els.push(t1('div', {class: 'foo'}, i)); } }
rest parameter
window.els.length = 0; for (let i = 0; i < 2000; i++) { if (i % 3 === 0) { els.push(t2('div', {class: 'foo'}, i, i + 1, i + 2)); } else { els.push(t2('div', {class: 'foo'}, i)); } }

Historical Performance Data aggregated from 6 community runs

Mobile Results:

Chrome 6 runs

arguments

1K/s

rest parameter

1K/s

View exact numbers

✓ arguments: 1,288 ops/sec
• rest parameter: 1,251 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
arguments
rest parameter

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/137.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 137 on Android

View result in a separate tab

rest parameter

3K/s

arguments

3K/s

View exact numbers

Test name	Executions per second
✓ rest parameter	2,776 Ops/sec
arguments	2,628 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

**Benchmark Definition**

The provided JSON represents a benchmark definition with two test cases: "rest parameters vs arguments (no extra args)". This benchmark tests the performance difference between using regular arguments and rest parameters in JavaScript functions.

**Options Compared**

In this benchmark, we have two options:

1. **Arguments**: The traditional way of passing arguments to a function.
2. **Rest Parameters**: A feature introduced in ECMAScript 2015 (ES6) that allows for the explicit use of a parameter list with a rest operator (`...`) after all other parameters.

**Pros and Cons**

### Arguments

Pros:

* Widely supported and used in existing codebases
* Simple to understand and implement

Cons:

* Less efficient than rest parameters due to unnecessary parameter checking and processing

### Rest Parameters

Pros:

* More concise and expressive syntax
* Can improve code readability and maintainability

Cons:

* May be less intuitive for developers without experience with rest parameters
* Requires support from all browsers and environments

**Library Usage**

In the provided benchmark definition, we see that the `t1` function uses `arguments`, while the `t2` function uses rest parameters (`...args`). The `els` array is used to store the results of each function call.

The `window.els.push()` method is likely a custom implementation or a placeholder for a more robust logging mechanism. Its purpose is not directly related to the performance comparison being tested.

**Special JS Features**

There are no special JavaScript features or syntaxes mentioned in this benchmark that require additional explanation. The use of rest parameters is standard and widely supported in modern JavaScript environments.

**Other Alternatives**

If you're interested in exploring alternative approaches to benchmarking JavaScript performance, consider the following options:

* **V8 Benchmark Suite**: A set of microbenchmarks designed to test specific aspects of V8, such as garbage collection, string processing, and more.
* **jsPerf**: A tool for benchmarking JavaScript code performance in various browsers and environments.
* **BenchmarkJS**: A framework for writing and running JavaScript benchmarks, providing a simple and consistent API for testing different scenarios.

By considering these alternatives and understanding the specific options being tested (arguments vs. rest parameters), you can gain insights into the performance characteristics of your own JavaScript codebases.

rest parameters vs arguments (no extra args) (version: 0)

Comparing performance of: `arguments vs rest parameter`

Created: 2 years ago by: Guest

Go to the latest result

arguments

rest parameter

Historical Performance Data aggregated from 6 community runs

Mobile Results:

Chrome 6 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

rest parameters vs arguments (no extra args) (version: 0)

Comparing performance of: arguments vs rest parameter

Created: 2 years ago by: Guest

Go to the latest result

arguments

rest parameter

Historical Performance Data aggregated from 6 community runs

Mobile Results:

Chrome 6 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

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Comparing performance of: `arguments vs rest parameter`