Benchmark: arguments vs array arg

Script Preparation code:

function test() {
    var v = [];
    for (var _i = 0; _i < arguments.length; _i++) {
        v[_i] = arguments[_i];
    }
  var different = false;
  for (var j = 0; j < v.length; j++) {
    if (j % 2 === 0) different = true;
  }
  return different;
}


function test2(v) {
  var different = false;
  for (var j = 0; j < v.length; j++) {
    if (j % 2 === 0) different = true;
  }
  return different;
}

​x
 
function test() {    var v = [];    for (var _i = 0; _i < arguments.length; _i++) {        v[_i] = arguments[_i];    }  var different = false;  for (var j = 0; j < v.length; j++) {    if (j % 2 === 0) different = true;  }  return different;}​​function test2(v) {  var different = false;  for (var j = 0; j < v.length; j++) {    if (j % 2 === 0) different = true;  }  return different;}​

Tests:

arguments

for(var i = 0; i < 10000; i++) {
  test(i, i + 1, i + 2, i + 3, i + 4, i + 5);
}

 
for(var i = 0; i < 10000; i++) {  test(i, i + 1, i + 2, i + 3, i + 4, i + 5);}

array arg

for(var i = 0; i < 10000; i++) {
  test2(i, i + 1, i + 2, i + 3, i + 4, i + 5);
}

 
for(var i = 0; i < 10000; i++) {  test2(i, i + 1, i + 2, i + 3, i + 4, i + 5);}

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Experimental features:

Memory measurements supported only in Chrome.
For precise memory measurements Chrome must be launched with --enable-precise-memory-info flag.
More information: Monitoring JavaScript Memory

Test case name	Result
arguments
array arg

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2025 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36

Browser/OS: Chrome 63 on Mac OS X 10.12.6

View result in a separate tab

Test name	Executions per second
arguments	759.7 Ops/sec
array arg	1324.9 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):

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

Benchmark Definition

The benchmark definition provides two scripts: test and test2. Both scripts have a similar structure, which is to iterate over an array of values (either from arguments or directly passed as an argument) and check if every other value in the array meets a certain condition (j % 2 === 0).

Options Compared

The benchmark compares two approaches:

Arguments: The script uses the arguments object, which is an array-like object that contains the arguments passed to the function. When called with multiple arguments, it creates an array of those arguments.
Array Argument: The script directly passes an array as an argument to the function.

Pros and Cons

Arguments:
- Pros: Easy to use, requires minimal code changes to modify the benchmark.
- Cons: Performance might be slower due to the overhead of creating an array-like object from individual arguments.
Array Argument:
- Pros: Can be faster, as it avoids the overhead of creating an array-like object and directly passes a pre-constructed array.
- Cons: Requires more code changes to modify the benchmark, and might not be suitable for all use cases.

Library

None explicitly mentioned in the provided code. However, it's worth noting that arguments is a built-in JavaScript object, while Array is a built-in JavaScript constructor.

Special JS Features or Syntax

The benchmark uses the for...of loop (not shown in the provided code) implicitly by using var _i = 0; _i < arguments.length;. This is not explicitly mentioned in the explanation, but it's an important detail to note. The for...of loop was introduced in ECMAScript 2015.

Other Considerations

Cache Locality: In both scripts, the iteration over the array uses a sequential approach, which means that each element is accessed in contiguous memory locations. This can lead to cache locality issues, where the CPU caches elements closer together.
Branch Prediction: The benchmark's condition j % 2 === 0 creates a branch prediction issue, as it's unclear whether the even index will be true or false on average.

Alternatives

If you wanted to write this benchmark, alternative approaches could include:

Using a loop that directly iterates over an array of values.
Using for...of loop with an explicit array of values.
Using Array.prototype.forEach() method, which is more concise and expressive than the original implementation.

Keep in mind that these alternatives might not be suitable for every use case or performance-critical benchmarking scenario.

LLMs can make mistakes. Check important info.

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

**Benchmark Definition**

The benchmark definition provides two scripts: `test` and `test2`. Both scripts have a similar structure, which is to iterate over an array of values (either from `arguments` or directly passed as an argument) and check if every other value in the array meets a certain condition (`j % 2 === 0`).

**Options Compared**

The benchmark compares two approaches:

1. **Arguments**: The script uses the `arguments` object, which is an array-like object that contains the arguments passed to the function. When called with multiple arguments, it creates an array of those arguments.
2. **Array Argument**: The script directly passes an array as an argument to the function.

**Pros and Cons**

* **Arguments**:
	+ Pros: Easy to use, requires minimal code changes to modify the benchmark.
	+ Cons: Performance might be slower due to the overhead of creating an array-like object from individual arguments.
* **Array Argument**:
	+ Pros: Can be faster, as it avoids the overhead of creating an array-like object and directly passes a pre-constructed array.
	+ Cons: Requires more code changes to modify the benchmark, and might not be suitable for all use cases.

**Library**

None explicitly mentioned in the provided code. However, it's worth noting that `arguments` is a built-in JavaScript object, while `Array` is a built-in JavaScript constructor.

**Special JS Features or Syntax**

The benchmark uses the `for...of` loop (not shown in the provided code) implicitly by using `var _i = 0; _i < arguments.length;`. This is not explicitly mentioned in the explanation, but it's an important detail to note. The `for...of` loop was introduced in ECMAScript 2015.

**Other Considerations**

* **Cache Locality**: In both scripts, the iteration over the array uses a sequential approach, which means that each element is accessed in contiguous memory locations. This can lead to cache locality issues, where the CPU caches elements closer together.
* **Branch Prediction**: The benchmark's condition `j % 2 === 0` creates a branch prediction issue, as it's unclear whether the even index will be true or false on average.

**Alternatives**

If you wanted to write this benchmark, alternative approaches could include:

1. Using a loop that directly iterates over an array of values.
2. Using `for...of` loop with an explicit array of values.
3. Using `Array.prototype.forEach()` method, which is more concise and expressive than the original implementation.

Keep in mind that these alternatives might not be suitable for every use case or performance-critical benchmarking scenario.

Related benchmarks:

arguments vs array arg (version: 0)

Comparing performance of: arguments vs array arg

Created: 7 years ago by: Guest

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