Benchmark: queryselectorall with assignment and without

HTML Preparation code:

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

Tests:

With variable assignment
const elements = document.querySelectorAll('.name'); elements.forEach(element => { console.log(element); });
Without 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
With variable assignment
Without 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_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.114 Safari/537.36

Browser/OS: Chrome 91 on Mac OS X 10.15.5

View result in a separate tab

Test name	Executions per second
With variable assignment	23595.7 Ops/sec
Without variable assignment	24290.3 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 and explain what's being tested.

**Benchmark Definition**

The benchmark is testing two different approaches to querying all elements with the class `name` in an HTML document using JavaScript:

1. **With variable assignment**: This approach assigns the result of `document.querySelectorAll('.name')` to a constant variable `elements`, which is then used as the input for the `forEach` loop.
2. **Without variable assignment**: This approach uses the `forEach` method directly on the result of `document.querySelectorAll('.name')`, without assigning it to a variable.

**Options being compared**

The two options being compared are:

* Using a variable to store the query result (with variable assignment) vs. using the `forEach` method directly on the query result (without variable assignment).

**Pros and Cons of each approach:**

* **With variable assignment**:
	+ Pros:
		- Easier to read and understand, as the intent of assigning a value to a variable is clear.
		- Can be more maintainable if the code needs to be modified or extended in the future.
	+ Cons:
		- May introduce unnecessary overhead due to the assignment operation.
* **Without variable assignment**:
	+ Pros:
		- Eliminates the need for an additional assignment operation, potentially reducing overhead.
	+ Cons:
		- May make the code more difficult to read and understand, as the intent of using `forEach` directly is not immediately clear.

**Other considerations:**

* The benchmark does not account for other factors that might affect performance, such as:
	+ The size and complexity of the HTML document being queried.
	+ The browser's internal optimizations or caching mechanisms.
	+ The specific JavaScript engine or runtime used by the browser.
* The benchmark uses a fixed class name `.name`, which may not be representative of real-world use cases where class names are dynamically generated.

**Library usage**

There is no explicit library mentioned in the benchmark, but it's worth noting that the `document.querySelectorAll` method is part of the DOM (Document Object Model) API, which is a built-in JavaScript API for interacting with web pages.

**Special JS feature or syntax**

There is no special JavaScript feature or syntax used in this benchmark. The code only uses standard JavaScript features like `const`, `let`, `forEach`, and `console.log`.

**Other alternatives**

If you were to write this benchmark yourself, you could consider adding other variations, such as:

* Using a different class name or attribute selector.
* Querying elements by ID instead of class name.
* Using a library like jQuery or a polyfill for older browsers that may not support modern JavaScript features.

However, keep in mind that the primary goal of this benchmark is to compare the performance of two specific approaches (with variable assignment and without), rather than exploring alternative scenarios.

Related benchmarks:

queryselectorall with assignment and without (version: 0)

Comparing performance of: With variable assignment vs Without variable assignment

Created: 3 years ago by: Guest

Jump to the latest result

With variable assignment

Without 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):