Benchmark: variable assignment test

HTML Preparation code:

<div class="name"><div class="name"><div class="name">

Tests:

variable assignment
const elements = document.querySelectorAll('.name'); elements.forEach(element => { console.log(element); });
non-variable assignment
document.querySelectorAll('.name').forEach(element => { console.log(element); });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
variable assignment
non-variable assignment

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.114 Safari/537.36

Browser/OS: Chrome 91 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
variable assignment	19801.3 Ops/sec
non-variable assignment	21904.8 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down what's happening in this JavaScript benchmarking test.

**What is being tested?**

The provided JSON represents two individual test cases for measuring the performance of variable assignment in JavaScript. The tests are designed to compare how fast it takes for JavaScript engines to iterate over an array of elements and log each element to the console.

**Options compared:**

There are two approaches being compared:

1. **Variable assignment**: `const elements = document.querySelectorAll('.name');` followed by `elements.forEach(element => { console.log(element); });`
2. **Non-variable assignment**: `document.querySelectorAll('.name').forEach(element => { console.log(element); });`

**Pros and cons of each approach:**

* **Variable assignment**:
	+ Pros:
		- Can potentially optimize the iteration process by using a cached variable.
		- May reduce overhead associated with re-executing the query selector multiple times.
	+ Cons:
		- Requires an additional step to declare a constant, which may introduce minor overhead.
		- May lead to confusion if not used carefully (e.g., re-declaring the same variable).
* **Non-variable assignment**:
	+ Pros:
		- Simplifies the code and eliminates the need for declaring a separate variable.
		- Can make the test more straightforward, as it doesn't require an extra step.
	+ Cons:
		- May lead to re-executing the query selector multiple times, which could introduce performance overhead.

**Library used:**

The `document.querySelectorAll('.name')` method uses the Web APIs to select elements based on their class name. The purpose of this library is to provide a convenient way to retrieve all elements that match a given CSS selector.

**Special JS feature or syntax:**

* **Const**: The `const` keyword is used to declare a constant variable, which ensures its value cannot be changed after it's declared.
* **Arrow functions**: The `=>` syntax is used to define an arrow function, which is a shorthand way of defining a function without the traditional `function` keyword.

**Other alternatives:**

There are alternative approaches that could be used for this benchmark:

1. Use a different data structure, such as an array literal or a Set.
2. Modify the query selector to use a different type of element (e.g., `document.createElement()` instead of `document.querySelectorAll()`)
3. Add additional operations between the assignment and iteration steps (e.g., modifying the elements before iterating over them).
4. Use a different engine or version of JavaScript.

Keep in mind that these alternatives might not be as representative of real-world scenarios, but they could provide interesting insights into how different approaches affect performance.

Related benchmarks:

variable assignment test (version: 0)

Comparing performance of: variable assignment vs non-variable assignment

Created: 3 years ago by: Guest

Jump to the latest result

variable assignment

non-variable assignment

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):