Benchmark: document.head vs document.getElementsByTagName("head")[0] fork12345

HTML Preparation code:

<head id="myHead">
<title>My title</title>
</head>

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

Latest run results:

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

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

The provided benchmark, hosted on MeasureThat.net, aims to compare the performance of different approaches for accessing the `<head>` element in HTML documents using JavaScript.

**Script Preparation Code**

There is no script preparation code specified in the benchmark definition. This means that the benchmark is only concerned with the execution time of accessing the `<head>` element and does not involve any additional setup or initialization.

**Html Preparation Code**

The benchmark uses a pre-defined HTML string, which includes an `<head>` element with an `id` attribute set to `"myHead"`. The HTML code is:
```html
<head id="myHead">
  <title>My title</title>
</head>
```
This HTML structure will be used as the basis for measuring the performance of accessing the `<head>` element.

**Test Cases**

There are three test cases, each representing a different approach to accessing the `<head>` element:

1. **`document.head || document.getElementsByTagName("head")[0];`**: This line of code attempts to access the `<head>` element using the `document.head` property. If `document.head` returns `null`, it falls back to using `document.getElementsByTagName("head")[0]`.
2. **`document.head;`**: This line of code simply accesses the `<head>` element using the `document.head` property.
3. **`document.getElementsByTagName("head")[0];`**: This line of code attempts to access the `<head>` element by iterating over all elements with the tag name `"head"` and selecting the first one.

**Pros and Cons**

* **Approach 1 (`document.head || document.getElementsByTagName("head")[0];`)**:
	+ Pros: If `document.head` is not available (e.g., in older browsers), this approach falls back to a safer alternative, ensuring that the benchmark is still meaningful.
	+ Cons: This approach may introduce additional overhead due to the fallback logic.
* **Approach 2 (`document.head;`)**:
	+ Pros: Simple and straightforward, with no additional overhead.
	+ Cons: May not be suitable for browsers where `document.head` is not available or returns `null`.
* **Approach 3 (`document.getElementsByTagName("head")[0];`)**:
	+ Pros: Directly accesses the `<head>` element, with no additional overhead.
	+ Cons: This approach may not be suitable for older browsers that do not support this syntax.

**Library and Special Features**

There are no libraries or special features mentioned in the benchmark. The test cases only involve standard JavaScript operations.

**Other Alternatives**

If MeasureThat.net were to add more alternatives, it could include:

* `document.querySelector("head")`: This approach uses a CSS selector to access the `<head>` element.
* `document.createElement("head").parentNode;`: This approach creates a new `<head>` element and accesses its parent node.

However, these alternatives would likely be added as additional test cases, rather than modifying the existing benchmark.

Related benchmarks:

document.head vs document.getElementsByTagName("head")[0] fork12345 (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):