Benchmark: document.head vs document.getElementsByTagName("head")[0] fork1234

HTML Preparation code:

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

Tests:

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

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Autogenerated LLM Summary (model llama3.2:3b, generated one year 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 approaches to accessing the `<head>` element of an HTML document using JavaScript:

1. `document.head`
2. `document.getElementsByTagName("head")[0]`

These two approaches are commonly used in JavaScript to access the head element, but they have different behaviors and use cases.

**Approach 1: `document.head`**

This approach uses the DOM (Document Object Model) property `document.head`, which returns a reference to the `<head>` element directly. This is generally considered the most efficient way to access the head element, as it avoids the need for iteration or searching through elements.

Pros:

* Fastest execution time
* Most accurate results

Cons:

* May not work in older browsers that don't support the DOM property `document.head`
* May not work in environments where the document head is not yet available (e.g., during page loading)

**Approach 2: `document.getElementsByTagName("head")[0]`**

This approach uses the `getElementsByTagName()` method to search for elements with the tag name "head" and returns an array of all matching elements. The first element in this array is then accessed using `[0]`. This approach can be useful when the head element may not be present or is dynamically added/removed.

Pros:

* Works in older browsers that don't support `document.head`
* Can handle cases where the head element is not yet available

Cons:

* Slower execution time compared to `document.head`
* May return null if no elements with the tag name "head" are found

**Library and Special JS Features**

In this benchmark, there is no library used explicitly. However, it's worth noting that some modern browsers like Chrome use a feature called "Shadow DOM" which allows for more efficient head access.

Additionally, there is no special JavaScript syntax being tested in this benchmark.

**Other Alternatives**

If you're looking for alternative approaches to accessing the `<head>` element, here are a few:

* `document.querySelector('head')`: This uses the `querySelector()` method, which returns the first element that matches the specified CSS selector. This approach is similar to `document.getElementsByTagName("head")[0]` but may be slower in some cases.
* `document.body.childNodes[1].parentNode`: This approach accesses the head element by traversing the DOM tree from the body element.

It's worth noting that these alternatives may have different pros and cons compared to the approaches tested in this benchmark.

Related benchmarks:

document.head vs document.getElementsByTagName("head")[0] fork1234 (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

No previous run results

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