Benchmark: Multiplying lists of vectors - with or without declaration

Script Preparation code:

var N = 1000000;

var vectors = [];
var vector;
for (var i = 0, li=N; i < li; ++i) {
	vectors.push( {x:Math.random(), y:Math.random(), z:Math.random()} );
}
abc=123
var abc=456

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:

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

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Let's break down the benchmark and its test cases.

**Benchmark Overview**

The benchmark measures the performance of multiplying lists of vectors in JavaScript, with two different approaches: with or without declaring the `vector` variable.

**Script Preparation Code**

The script preparation code generates a list of 1 million vectors with random x, y, and z coordinates. The code also declares a variable `abc` twice, but this declaration is not used in the benchmarking loop.

**Html Preparation Code**

There is no HTML preparation code provided.

**Test Cases**

There are two test cases:

1. **"with duplicate declaration"`**: This test case uses the same variable declaration syntax as the script preparation code: `var vector;`. The benchmarking loop iterates over the list of vectors, and for each iteration, it modifies the `vector` variable by multiplying its x, y, and z coordinates by 2.
2. **"without duplicate declaration"`**: This test case uses a different variable declaration syntax: only declaring the `vector` variable within the loop. The benchmarking loop iterates over the list of vectors, and for each iteration, it modifies the `vector` variable by multiplying its x, y, and z coordinates by 2.

**Library and Special Features**

There are no external libraries used in this benchmark. However, the use of `var` declarations with the same name (e.g., `abc = 123` followed by a reassignment) is an example of a common JavaScript feature known as "variable hoisting" or "temporal dead zone". This can lead to unexpected behavior and performance issues in some cases.

**Pros and Cons**

Here are some pros and cons for each approach:

**With Duplicate Declaration:**

Pros:

* May be more readable and maintainable, especially for developers familiar with this syntax.
* Can reduce the number of declarations needed.

Cons:

* Can lead to increased overhead due to variable hoisting and reassignment.
* May cause performance issues if used extensively in loops.

**Without Duplicate Declaration:**

Pros:

* Reduces the risk of performance issues caused by variable hoisting and reassignment.
* Avoids potential readability issues with multiple declarations having the same name.

Cons:

* May require more careful declaration ordering to avoid variable scope issues.
* Can increase the number of declarations needed.

**Other Alternatives**

If you need to multiply lists of vectors in JavaScript, here are some alternative approaches:

1. **Using `for...of` loops**: This can simplify the code and eliminate the need for explicit loop variables.
2. **Using `let` or `const` instead of `var`**: These declarations provide more predictable behavior and better support for modern JavaScript features.
3. **Avoiding unnecessary variable assignments**: Minimize the number of reassignments to variables, as this can lead to performance issues.

Overall, the choice of approach depends on the specific requirements of your project and your team's familiarity with different coding styles and syntax.

Related benchmarks:

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

Comparing performance of: with duplicate declaration vs without duplicate declaration

Created: 9 years ago by: Guest

Jump to the latest result

with duplicate declaration

without duplicate declaration

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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