Benchmark: getElementById querySelector

HTML Preparation code:

<div id="my-id"></div>

Tests:

querySelector
document.querySelector("#my-id")
getElementById
document.getElementById("my-id")

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
querySelector
getElementById

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

I'll break down the benchmark and explain what's being tested, compared, and what pros and cons are associated with each approach.

**Benchmark Overview**

The benchmark is designed to compare the performance of two DOM query methods in JavaScript: `document.getElementById` (getElementById) and `document.querySelector`. The test case creates a simple HTML element (`<div id="my-id"></div>`) and measures how long it takes to retrieve this element using each method.

**Script Preparation Code**

The script preparation code is empty, which means that the benchmark doesn't require any specific setup or initialization before running the tests. This allows for a clean comparison of the two query methods.

**Html Preparation Code**

The HTML preparation code creates a simple `div` element with an ID (`"my-id"`). This element will be used as the target for both query methods.

**Individual Test Cases**

There are two test cases:

1. **querySelector**: Measures how long it takes to retrieve the element using the `querySelector` method.
2. **getElementById**: Measures how long it takes to retrieve the element using the `getElementById` method.

**Options Compared**

The benchmark compares two options:

1. **querySelector**: Uses the `querySelector` method, which returns the first matching element. This method is often preferred over `getElementById` because it's more flexible and can be used with CSS selectors.
2. **getElementById**: Uses the `getElementById` method, which returns a single element by its ID.

**Pros and Cons**

Here are some pros and cons of each approach:

* **querySelector**:
	+ Pros: More flexible, can be used with CSS selectors, less error-prone than `getElementById`.
	+ Cons: May not return the expected result if there are multiple elements with the same selector.
* **getElementById**:
	+ Pros: Returns a single element by its ID, no need to worry about CSS selectors.
	+ Cons: Less flexible, may require more code to handle different cases.

**Library and Purpose**

The `querySelector` method is part of the W3C DOM Standard (Selectors API). It's designed to make it easier to select elements in HTML documents using CSS-like selectors. The purpose of this method is to provide a more efficient and flexible way to retrieve elements from the DOM.

**Special JS Feature/Syntax**

None of the test cases use any special JavaScript features or syntax beyond the standard query methods.

**Other Alternatives**

If you want to test different query methods, here are some alternatives:

1. `document.getElementsByTagName`: Returns an HTMLCollection of all elements with the specified tag name.
2. `document.querySelectorAll`: Similar to `querySelector`, but returns all matching elements instead of just the first one.
3. `document.querySelectorAll`: Similar to `querySelectorAll`, but uses CSS selectors.

Keep in mind that these alternatives may have different performance characteristics and usage patterns compared to `querySelector` and `getElementById`.

**Benchmarking Considerations**

When benchmarking JavaScript query methods, consider the following:

1. **Cache and Reuse**: If possible, cache the results of expensive computations or queries to avoid repeated execution.
2. **Optimize for Performance**: Optimize the code for performance by reducing unnecessary computations or using more efficient data structures.
3. **Test for Edge Cases**: Test the query methods for edge cases, such as retrieving an element that doesn't exist in the DOM.

By following these guidelines and considering the pros and cons of each approach, you can create effective benchmarks to compare JavaScript query methods like `document.getElementById` and `document.querySelector`.

Latest run results:

Run details: (Test run date: 6 years ago)

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:62.0) Gecko/20100101 Firefox/62.0

Browser/OS: Firefox 62 on Ubuntu

View result in a separate tab

Test name	Executions per second
querySelector	2654656.0 Ops/sec
getElementById	5428652.5 Ops/sec

Related benchmarks:

getElementById querySelector (version: 0)

Comparing performance of: querySelector vs getElementById

Created: 6 years ago by: Guest

Jump to the latest result

querySelector

getElementById

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):