Benchmark: Multiplying lists of vectors - with or without declaration

Script Preparation code:

var N = 100000;

var vectors = [];

for (var i = 0, li=N; i < li; ++i) {
	vectors.push( {x:Math.random(), y:Math.random(), z:Math.random()} );
}

Tests:

with duplicate declaration
var vector; for (var i = 0, li=vectors.length; i < li; ++i) { vector = vectors[i]; vector.x = 2 * vector.x; vector.y = 2 * vector.y; vector.z = 2 * vector.z; }
without duplicate declaration
for (var i = 0, li=vectors.length; i < li; ++i) { vector = vectors[i]; vector.x = 2 * vector.x; vector.y = 2 * vector.y; vector.z = 2 * vector.z; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
with duplicate declaration
without duplicate declaration

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 8 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.99 Safari/537.36

Browser/OS: Chrome 54 on Windows

View result in a separate tab

Test name	Executions per second
with duplicate declaration	59.5 Ops/sec
without duplicate declaration	4.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark definition and test cases to understand what is being tested.

**Benchmark Definition**

The benchmark measures the performance of multiplying lists of vectors in JavaScript, with two variations:

1. **With or without declaration**: The first variation declares a variable `vector` before using it in a loop.
2. **Without duplicate declaration**: The second variation does not declare a separate variable `vector` and instead assigns new values to the existing `vector` object inside the loop.

**Script Preparation Code**

The script preparation code generates an array of 100,000 vectors with random x, y, and z coordinates. This is done using two loops: one to create the arrays, and another ( commentd out) for some reason that will be looked at later

**Html Preparation Code**

There is no HTML preparation code provided.

**Individual Test Cases**

There are two test cases:

1. **"with duplicate declaration"`**: In this case, a variable `vector` is declared outside the loop and then assigned new values to it inside the loop.
2. **"without duplicate declaration"`**: In this case, there is no separate `vector` variable declared, and instead, the existing object in the array is modified directly.

**Library Used**

There is no explicit library mentioned, but some common libraries like Lodash are commonly used for vector operations (but not present here).

**Special JS Feature or Syntax**

The benchmark does not explicitly use any special JavaScript features or syntax. However, it's worth noting that using `const` and `let` keywords to declare variables has become a best practice in modern JavaScript.

**Pros and Cons of Approaches**

1. **With duplicate declaration**: This approach can be faster because the variable is declared outside the loop, reducing the overhead of declaring and redeclaring variables.
	* Pros: Reduces overhead of variable declaration, can be slightly faster
	* Cons: Can lead to memory leaks if not used carefully, makes the code harder to understand for some developers
2. **Without duplicate declaration**: This approach avoids declaring a separate variable outside the loop, reducing memory usage and making the code easier to reason about.
	* Pros: Reduces memory usage, makes the code easier to understand
	* Cons: Can be slightly slower due to the overhead of modifying existing objects

**Other Considerations**

1. **Scoping**: The `with` keyword is not used here, but it can be useful for encapsulating variables and avoiding naming conflicts.
2. **Memory Allocation**: In modern JavaScript engines, memory allocation is typically done automatically by the engine, so declaring variables inside loops does not have a significant impact on performance.

**Alternatives**

Other ways to multiply lists of vectors could include:

1. Using `forEach` loop: This approach would avoid declaring separate variables and use the existing object directly.
2. Using a library like Lodash for vector operations
3. Using `map` function: This approach would create new objects instead of modifying the existing ones, which can be more memory-efficient.

However, without knowing the exact requirements or constraints of the benchmark, it's difficult to say which approach is best suited.

Related benchmarks:

Multiplying lists of vectors - with or without declaration (version: 0)

Comparing performance of: with duplicate declaration vs without duplicate declaration

Created: 8 years ago by: Guest

Jump to the latest result

with duplicate declaration

without duplicate declaration

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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