Benchmark: getElementById vs querySelector vs map.get

HTML Preparation code:

<div id="test-id" />

<script>
  const map = new Map()
</script>

Script Preparation code:

map.set("test-id", document.getElementById("test-id"))

Tests:

getElementById
const el = document.getElementById("test-id")
querySelector
const el = document.querySelector("#test-id")
map.get
const el = map.get("test-id")

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
getElementById
querySelector
map.get

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/143.0.0.0 Safari/537.36

Browser/OS: Chrome 143 on Windows

View result in a separate tab

Test name	Executions per second
getElementById	41279016.0 Ops/sec
querySelector	8087415.0 Ops/sec
map.get	169730592.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the explanation of the provided benchmark.

**Benchmark Overview**

The provided benchmark measures the performance of three different approaches to retrieve an HTML element by its ID: `getElementById`, `querySelector`, and `map.get`. The benchmark is designed to compare these approaches in a controlled environment, providing insights into their relative performance on different browsers and devices.

**Library Used**

In this benchmark, the `Map` data structure from JavaScript's built-in collection API is used. A `Map` is an object that stores key-value pairs, where each key is unique and maps to a specific value. In this case, the `map.get()` method is used to retrieve the value associated with a given key (in this case, the ID of the HTML element).

**Options Compared**

The three options being compared are:

1. **`getElementById`**: This approach uses the DOM's built-in method to retrieve an element by its ID.
2. **`querySelector`**: This approach uses the `querySelector()` method to select elements based on a CSS selector, including elements with IDs.
3. **`map.get`**: As mentioned earlier, this approach uses the `Map` data structure to retrieve the value associated with a given key (the element's ID).

**Pros and Cons**

Here are some pros and cons of each approach:

1. **`getElementById`**:
	* Pros: Simple, widely supported, and well-established.
	* Cons: Can be slower than other approaches, especially in older browsers or when dealing with complex DOM structures.
2. **`querySelector`**:
	* Pros: Flexible, allowing for more complex selection scenarios, and can be faster than `getElementById`.
	* Cons: May not work as expected in older browsers that don't support modern CSS selectors.
3. **`map.get`**:
	* Pros: Fast, consistent, and reliable, especially when working with large datasets or frequent lookups.
	* Cons: Requires creating a `Map` instance and storing the elements to be retrieved, which can add overhead.

**Other Considerations**

When choosing between these approaches, consider factors like:

* Browser support: If you need to support older browsers, `getElementById` might be a safer choice. For modern browsers with CSS selectors, `querySelector` could be a better option.
* DOM complexity: In complex DOM structures, `querySelector` or other dynamic methods might be more suitable than `getElementById`.
* Performance-critical code: If you're working on performance-critical code, consider using `map.get` for its speed advantages.

**Special JS Feature**

There is no special JavaScript feature or syntax explicitly used in this benchmark. However, the use of modern CSS selectors like `querySelector` assumes a good understanding of modern web development principles and standards.

If you'd like to explore alternative approaches, consider:

* Using other DOM traversal methods, such as `document.querySelectorAll()` or `Element.getElementsByTagName()`.
* Implementing custom lookup mechanisms using arrays or other data structures.
* Leveraging browser-specific APIs or extensions for faster performance.

Related benchmarks:

getElementById vs querySelector vs map.get (version: 0)

Comparing performance of: getElementById vs querySelector vs map.get

Created: 2 years ago by: Guest

Jump to the latest result

getElementById

querySelector

map.get

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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