Benchmark: getElementById vs querySelector again

HTML Preparation code:

<div id="div"></div>

Script Preparation code:

div.innerHTML = Array(1000).fill(0).map((el, i) => `<div id="id${i}" class="test${i}"></div>`)

Tests:

getElementById
Array(1000).fill(0).map((el, i) => document.getElementById(`id${i}`).className)
querySelector
Array(1000).fill(0).map((el, i) => document.querySelector(`#id${i}`).className)

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: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Windows

View result in a separate tab

Test name	Executions per second
getElementById	1387.7 Ops/sec
querySelector	47.4 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 world of JavaScript microbenchmarks on MeasureThat.net.

**Benchmark Overview**

The benchmark is designed to compare the performance of `document.getElementById` and `document.querySelector` in selecting elements by ID. The test case consists of two individual tests:

1. `getElementById`
2. `querySelector`

Both tests create an array of 1000 elements, each with a unique ID (`id${i}`) and a class name (`test${i}`). The script preparation code generates these elements using JavaScript, while the HTML preparation code creates a container element (`div`) to hold the generated elements.

**Benchmarking Options**

The two options being compared are:

1. **`document.getElementById`**: This method retrieves an element by its ID.
2. **`document.querySelector`**: This method retrieves one or more elements that match a specific CSS selector (in this case, `#id${i}`).

**Pros and Cons of Each Approach**

**`document.getElementById`**

Pros:

* Fast and efficient, especially for single-element lookups.
* Simple to use and understand.

Cons:

* Can be slower for multiple element lookups due to the need to traverse the DOM tree.
* Not as flexible as `querySelector`, as it requires a specific ID.

**`document.querySelector`**

Pros:

* Faster for multiple element lookups, as it uses a more efficient algorithm.
* More flexible than `getElementById`, as it can match elements using CSS selectors.

Cons:

* Can be slower for single-element lookups due to the need to parse the CSS selector.
* More complex to use and understand, especially for those unfamiliar with CSS selectors.

**Library Usage**

There is no library used in this benchmark. Both `document.getElementById` and `document.querySelector` are built-in methods of the Document object.

**Special JavaScript Feature or Syntax**

None mentioned.

**Other Considerations**

When evaluating the performance of these two methods, it's essential to consider the following factors:

* The size of the dataset (1000 elements in this case).
* The complexity of the CSS selector (in this case, a simple ID-based selector).
* The browser and device platform used for testing.

**Alternatives**

If you're looking for alternative benchmarking tools or approaches, consider the following options:

1. **Benchmark.js**: A popular JavaScript benchmarking library that provides a simple way to write and run benchmarks.
2. **jsperf**: A web-based benchmarking tool that allows you to compare the performance of different JavaScript code snippets.
3. **V8 Benchmark Suite**: An official benchmarking suite provided by Google V8, which tests the performance of various JavaScript engines.

In conclusion, the MeasureThat.net benchmark provides a clear comparison between `document.getElementById` and `document.querySelector`, highlighting their respective strengths and weaknesses. By understanding the pros and cons of each approach, you can make informed decisions about which method to use in your own JavaScript applications.

Related benchmarks:

getElementById vs querySelector again (version: 0)

Comparing performance of: getElementById vs querySelector

Created: 6 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):