Benchmark: check args length

HTML Preparation code:

<!--your preparation HTML code goes here-->

Script Preparation code:

function a(){
return arguments.length > 3
}
function b(){
return 3 in arguments
}

Tests:

length
a() a(1) a(1,1) a(1,1,1) a(1,1,1,1)
"in" operator
b() b(1) b(1,1) b(1,1,1) b(1,1,1,1)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
length
"in" operator

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/137.0.0.0 Safari/537.36

Browser/OS: Chrome 137 on Linux

View result in a separate tab

Test name	Executions per second
length	195858784.0 Ops/sec
"in" operator	185499200.0 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 11 months ago):

LLMs can make mistakes. Check important info.

The benchmark focuses on comparing two different methods of determining the length of the `arguments` object in JavaScript functions: using the `arguments.length` property and the `in` operator.

### Benchmark Overview
The provided benchmark consists of two JavaScript functions, `a` and `b`, which evaluate the length of the `arguments` object in terms of performance:
- **Function `a`:** Checks if the number of arguments is greater than 3 by using `arguments.length`.
- **Function `b`:** Checks if the index `3` exists in the `arguments` object using the `in` operator.

### Test Cases
1. **Test Name:** "length"
   - **Benchmark Definition:** 
     - Calls the function `a()` with different numbers of arguments: `a()`, `a(1)`, `a(1,1)`, `a(1,1,1)`, and `a(1,1,1,1)`.
     
2. **Test Name:** "\"in\" operator"
   - **Benchmark Definition:** 
     - Calls the function `b()` with the same number of arguments as in test case one: `b()`, `b(1)`, `b(1,1)`, `b(1,1,1)`, and `b(1,1,1,1)`.

### Performance Results
- **Executions Per Second for `a()` (length check):** 195,858,784
- **Executions Per Second for `b()` (in operator check):** 185,499,200

### Comparison of Approaches
- **`arguments.length` (Function `a`):**
  - **Pros:**
    - Directly retrieves the length of the `arguments` object, which is straightforward and generally optimized by JavaScript engines.
    - More readable and clear in intent, which improves the maintainability of the code.
  - **Cons:**
    - None significant in terms of performance; however, it does involve a direct property access which might theoretically slow down in very specific edge cases (not typically seen in practice).

- **`in` Operator (Function `b`):**
  - **Pros:**
    - Can be used to check any property within an object, which makes it versatile in certain contexts.
  - **Cons:**
    - Generally less efficient for simply counting arguments. It requires checking for the existence of a specific index rather than retrieving a property length, making it slower in this specific context.
    - Less clear in code readability since it introduces a concept of existence rather than quantity, potentially confusing the intent.

### Alternatives
Other alternatives to determine the number of arguments passed to a function include:
- **Spread Syntax:** Using the rest operator (e.g., `function c(...args) { return args.length; }`). This would create an array of arguments and return its length but introduces array construction overhead.
  
- **Array.from(arguments):** Similar to spread syntax, this converts the `arguments` object into an actual array, allowing more array methods to be used but also introduces extra overhead.

### Conclusion
The benchmark shows that accessing `arguments.length` is a more performant approach for checking the number of arguments in function calls compared to using the `in` operator. The tests indicate that while both methods eventually achieve the same goal, `arguments.length` is significantly faster in this context. Understanding and using the correct method for checking argument counts is essential for writing efficient JavaScript code.

Related benchmarks:

check args length (version: 1)

Comparing performance of: length vs "in" operator

Created: 11 months ago by: Guest

Jump to the latest result

length

"in" operator

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 11 months ago):