Benchmark: getElementById vs querySelector (ver.2023.05)

HTML Preparation code:

<html>
  <body>
    <div id="test"></div>
  </body>
</html>

Tests:

getElementById
document.getElementById("test");
querySelector
document.querySelector("#test");

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
getElementById
querySelector

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/121.0.0.0 Safari/537.36 Edg/121.0.0.0

Browser/OS: Chrome 121 on Windows

View result in a separate tab

Test name	Executions per second
getElementById	3555433.8 Ops/sec
querySelector	2160137.8 Ops/sec

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 Overview**

The test is comparing two ways to select an HTML element by its ID: `document.getElementById` (aliased as "getElementById") and `document.querySelector` (aliased as "querySelector"). The benchmark aims to determine which method is faster.

**Options Compared**

Two options are being compared:

1. **document.getElementById**: This function takes a string argument representing the ID of the element to be retrieved, and returns the corresponding HTML element.
2. **document.querySelector**: This function also takes a string argument representing the selector (in this case, an ID) of the element to be retrieved, but it uses CSS selectors to achieve the result.

**Pros and Cons**

* `document.getElementById`:
	+ Pros: Simple, straightforward, and widely supported across browsers.
	+ Cons: Can be slower for more complex queries or when used with less efficient algorithms (e.g., using querySelectorAll).
* `document.querySelector`:
	+ Pros: More flexible and powerful than `getElementById`, allowing for more complex selectors and better support for modern web development standards like CSS3.
	+ Cons: May have performance overhead due to the complexity of its algorithm or the need to parse CSS selectors.

**Library Usage**

Neither `document.getElementById` nor `document.querySelector` relies on a specific library. These are native JavaScript functions built into the DOM API.

**Special JS Features or Syntax**

This benchmark does not use any special JavaScript features or syntax, such as async/await, Promise, or modern ES modules (ES6+). The code is straightforward and uses basic synchronous operations.

**Other Alternatives**

If you wanted to test these methods under different scenarios:

1. **Dynamic element generation**: Test how `document.getElementById` and `querySelector` perform when dealing with dynamically generated elements.
2. **Nested selectors**: Test using more complex CSS selectors, like `querySelectorAll`, to see if the performance difference remains significant.
3. **Async/await usage**: Test how these methods perform when used within async/await statements or Promises.

Keep in mind that benchmarking JavaScript performance can be complex and dependent on many factors, such as browser version, hardware, and environment.

Related benchmarks:

getElementById vs querySelector (ver.2023.05) (version: 0)

Comparing performance of: getElementById vs querySelector

Created: 2 years ago by: Guest

Jump to the latest result

getElementById

querySelector

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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