Benchmark: getElementById, querySelector, querySelectorAll and with if

HTML Preparation code:

<div id="test">Test</div>

Tests:

getElementById
document.getElementById("test");
querySelector
document.querySelector("#test")
querySelectorAll
document.querySelectorAll("#test")
with iF
var sel = '#test'; if (sel[0] === '#') { document.getElementById("test"); } else { document.querySelectorAll("#test") }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
getElementById
querySelector
querySelectorAll
with iF

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 28 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and its test cases.

**Benchmark Overview**

The benchmark is designed to compare the performance of three DOM query methods: `getElementById`, `querySelector`, and `querySelectorAll`. Additionally, it tests how these methods perform when used with an "if" statement, which introduces a conditional branch in the JavaScript code. The benchmark uses JavaScript microbenchmarks, allowing users to create and run their own benchmarks.

**Test Cases**

There are four test cases:

1. **getElementById**: This test case simply calls `document.getElementById("test")` without any conditionals or additional logic.
2. **querySelector**: This test case calls `document.querySelector("#test")`, which is similar to `getElementById` but uses the query selector syntax.
3. **querySelectorAll**: Similar to `querySelector`, this test case calls `document.querySelectorAll("#test")`, but it returns all elements matching the selector, rather than just the first one.
4. **with if**: This test case adds an "if" statement that checks if the query result is equal to "#". If true, it calls `document.getElementById("test")`; otherwise, it calls `document.querySelectorAll("#test")`. This introduces a conditional branch in the JavaScript code.

**Options Compared**

The benchmark compares four different approaches:

1. **ElementById**: The simplest approach, which directly uses `document.getElementById` to retrieve an element by its ID.
2. **querySelector**: A more expressive syntax for querying DOM elements, using the query selector API.
3. **querySelectorAll**: Similar to `querySelector`, but returns all matching elements instead of just the first one.
4. **with if**: Introduces a conditional branch in the JavaScript code, which can affect performance.

**Pros and Cons**

Here's a brief summary of the pros and cons of each approach:

* **ElementById**:
	+ Pros: Simple, efficient, and widely supported.
	+ Cons: Can be slower than other methods if the element is not found or if it requires more DOM traversal.
* **querySelector**:
	+ Pros: More expressive syntax, can return multiple matches, and often faster than `getElementById`.
	+ Cons: May require additional CSS styles or attribute manipulation, which can add complexity.
* **querySelectorAll**:
	+ Pros: Returns all matching elements, which can be useful in certain scenarios.
	+ Cons: Can be slower than `querySelector` if the element is not found or requires more DOM traversal.
* **with if**:
	+ Pros: Introduces a conditional branch, which can affect performance.
	+ Cons: Adds unnecessary complexity and may lead to slower execution times.

**Libraries and Special Features**

None of the test cases explicitly use any libraries beyond what's built into JavaScript. However, it's worth noting that some of these methods (e.g., `querySelector`) rely on CSS selectors, which can involve additional processing or attribute manipulation.

**Alternatives**

Some alternative approaches to DOM query methods include:

1. **DOM Traversals**: Manual iteration over the DOM tree using `getElementsByClassName`, `getElementsByTagName`, or other traversal methods.
2. **Library-based solutions**: Using dedicated libraries like jQuery, React, or Angular, which provide their own DOM query mechanisms and often offer performance optimizations.
3. **Custom solutions**: Developing custom JavaScript functions or modules for specific use cases, which can provide more control but may also introduce additional complexity.

Keep in mind that these alternatives often require significant changes to the codebase and may not be suitable for all projects.

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36

Browser/OS: Chrome 124 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
getElementById	9159575.0 Ops/sec
querySelector	5668855.0 Ops/sec
querySelectorAll	2801471.8 Ops/sec
with iF	9110585.0 Ops/sec

Related benchmarks:

getElementById, querySelector, querySelectorAll and with if (version: 0)

Comparing performance of: getElementById vs querySelector vs querySelectorAll vs with iF

Created: 6 years ago by: Guest

Jump to the latest result

getElementById

querySelector

querySelectorAll

with iF

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 28 days ago):