Benchmark: document.head vs document.getElementsByTagName("head")[0] fork123

HTML Preparation code:

<html>
<head id="myHead">
<title>My title</title>
</head>
<body><p id="demo"></p>
</body>
</html>

Tests:

1
var css = document.head || document.getElementsByTagName("head")[0];
2
var css = document.head;
3
var css = document.getElementsByTagName("head")[0];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
1
2
3

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36

Browser/OS: Chrome 120 on Windows

View result in a separate tab

Test name	Executions per second
1	5670005.0 Ops/sec
2	5183928.5 Ops/sec
3	2461358.2 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the benchmark and its options for you.

**Benchmark Definition**

The benchmark is designed to compare three different ways of accessing the `<head>` element in an HTML document:

1. `document.head`
2. `document.getElementsByTagName("head")[0]`
3. A combination of both, using the OR operator (`||`).

**Options Compared**

* Option 1: Direct access to the `<head>` element using `document.head`.
	+ Pros:
		- Fast and efficient, as it directly accesses a single property.
		- May be cached by browsers, reducing overhead.
	+ Cons:
		- May not work in older browsers that don't support `document.head`.
* Option 2: Accessing the `<head>` element using `document.getElementsByTagName("head")[0]`.
	+ Pros:
		- Works in older browsers that don't support `document.head`.
		- Can provide a fallback if `document.head` is not available.
	+ Cons:
		- May be slower than direct access, as it involves an extra step to retrieve the first element from the array returned by `getElementsByTagName`.
		- May incur additional overhead due to the array lookup and iteration.
* Option 3: Combination of both using the OR operator (`||`).
	+ Pros:
		- Provides a single expression that handles both cases (modern browsers and older ones).
		- Can be more concise than option 2.

**Library/ Framework**

None explicitly mentioned, but `document` is a part of the DOM (Document Object Model) API, which is a standard API for working with HTML documents in JavaScript.

**Special JS Features/Syntax**

The benchmark doesn't use any special JavaScript features or syntax beyond what's typically available in modern browsers. However, it does rely on the fact that `document.head` and `document.getElementsByTagName("head")[0]` are properties of the `document` object.

**Other Alternatives**

If you wanted to test alternative approaches, some possible options could include:

* Using `document.querySelector("#myHead")` or `document.getElementById("myHead")` instead of accessing the `<head>` element directly.
* Comparing performance with different methods for handling cases where the `<head>` element is not available (e.g., using a fallback element).
* Testing the performance impact of using various caching mechanisms, such as memoization or caching in a library.

Keep in mind that adding more test cases and alternatives might make the benchmark more complex and harder to maintain.

Related benchmarks:

document.head vs document.getElementsByTagName("head")[0] fork123 (version: 0)

Comparing performance of: 1 vs 2 vs 3

Created: 7 years ago by: Guest

Jump to the latest result

1

2

3

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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