Benchmark: DOM Retrieval vs DOM element assignment

HTML Preparation code:

<div id="superfoo"></div<

Tests:

Fetch from DOM
var i; for(i = 0; i < 10000; i++) { var element = document.getElementById("superfoo"); var className = element.className; }
Assign to variable
var element = document.getElementById("superfoo"); var i; for(let i = 0; i < 10000; i++) { var className = element.className; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Fetch from DOM
Assign to variable

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.

**What is being tested?**

The primary objective of this benchmark is to compare the performance of two approaches:

1. Assigning a DOM element to a variable (e.g., `var element = document.getElementById("superfoo");`).
2. Fetching a DOM element from the Document Object Model (DOM) each time (e.g., `var element = document.getElementById("superfoo"); var className = element.className;`).

**Options compared**

In this benchmark, we have two test cases:

* **Fetch from DOM**: This approach involves fetching the DOM element and then using its properties (in this case, `className`) in a loop.
* **Assign to variable**: This approach assigns the result of `document.getElementById("superfoo")` to a variable (`element`) and then uses that variable's properties in a loop.

**Pros and cons**

**Fetch from DOM:**

Pros:

* More intuitive and straightforward way of accessing DOM elements
* May be more cache-friendly, as the element is only fetched once

Cons:

* May result in repeated DOM queries for each iteration, leading to performance degradation due to unnecessary DOM manipulation
* Requires extra operations (e.g., `className` property access) that may add overhead

**Assign to variable:**

Pros:

* Avoids repeated DOM queries, as the element is assigned to a variable once
* May result in better cache locality, as the same variable is reused

Cons:

* More complex and less intuitive way of accessing DOM elements
* Requires more memory allocation and storage for the variable

**Other considerations**

* The benchmark does not account for other factors that might affect performance, such as:
	+ Browser-specific optimizations or limitations
	+ Network latency or other external dependencies
	+ Different hardware configurations (e.g., CPU, GPU)
	+ Memory constraints

**Library usage**

There is no explicit library mentioned in the provided code. However, it's essential to note that `document.getElementById` and other DOM-related methods are part of the browser's API, which can be considered a built-in library.

**Special JS features or syntax**

There are no special JavaScript features or syntax highlighted in this benchmark. The focus is on comparing two straightforward approaches to accessing DOM elements.

**Alternatives**

If you were to design an alternative benchmark for this use case, you might consider exploring other aspects of DOM manipulation, such as:

* Using different DOM query methods (e.g., `querySelector`, `querySelectorAll`)
* Comparing performance with and without using libraries or frameworks (e.g., jQuery)
* Investigating the impact of various caching strategies or memoization techniques on performance
* Analyzing the effects of different browser versions, engine variants, or hardware configurations on performance

Keep in mind that these alternatives would require significant changes to the benchmark's design, scope, and methodology.

Related benchmarks:

DOM Retrieval vs DOM element assignment (version: 0)

Test to see whether it is more performant to assign a DOM element to a variable or fetch it from the DOM each time.

Comparing performance of: Fetch from DOM vs Assign to variable

Created: 4 years ago by: Guest

Jump to the latest result

Fetch from DOM

Assign to variable

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):