Benchmark: getElementById vs getElementsByClassName vs getElementsByName2

Script Preparation code:

let Zoo = document.createElement("div"); 

for (let i=0;i<1000;i++){
	let foo = document.createElement("div");                        
	foo.id= "foo";
	foo.classList.add("foo");
	foo.name= "foo";
	Zoo.appendChild(foo);     
}

Tests:

getElementById
for (let i=0;i<1000;i++){ let bar1 = document.getElementById("foo"); }
getElementsByClassName
for (let i=0;i<1000;i++){ let bar2 = document.getElementsByClassName("foo"); }
getElementsByClassName[0]
for (let i=0;i<1000;i++){ let bar3 = document.getElementsByClassName("foo")[100]; }
getElementsByName
for (let i=0;i<1000;i++){ let bar4 = document.getElementsByName("foo"); }
getElementsByName[0]
for (let i=0;i<1000;i++){ let bar5 = document.getElementsByName("foo")[100]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
getElementById
getElementsByClassName
getElementsByClassName[0]
getElementsByName
getElementsByName[0]

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Android 12; Mobile; rv:126.0) Gecko/126.0 Firefox/126.0

Browser/OS: Firefox Mobile 126 on Android

View result in a separate tab

Test name	Executions per second
getElementById	7667.8 Ops/sec
getElementsByClassName	7478.9 Ops/sec
getElementsByClassName[0]	2672.3 Ops/sec
getElementsByName	7266.0 Ops/sec
getElementsByName[0]	2581.5 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the provided benchmark JSON and explain what's being tested, compared, and the pros and cons of each approach.

**Benchmark Definition**

The benchmark definition is an object that describes the test to be performed. In this case:

* `Name`: The name of the benchmark.
* `Description`: An optional description of the benchmark (not provided in this example).
* `Script Preparation Code`: A JavaScript code snippet that prepares the environment for the benchmark. This code creates a container element (`Zoo`) and appends 1000 child elements with IDs, classes, and names set to "foo".
* `Html Preparation Code`: An optional HTML code snippet that prepares the HTML document for the benchmark (not provided in this example).

**Individual Test Cases**

The test cases are an array of objects that define each individual test. Each object contains:

* `Benchmark Definition`: The actual JavaScript code that will be executed during the test.
* `Test Name`: A descriptive name for the test.

In this case, there are four test cases:

1. `getElementById`
2. `getElementsByClassName`
3. `getElementsByName[0]` (note: `getElementsByName` is not a standard method in JavaScript; it's likely a custom or proprietary method)
4. `getElementsByClassName[0]`

**What's Being Tested**

In essence, the benchmark is testing the performance of three different methods to retrieve elements from an HTML document:

1. `getElementById`
2. `getElementsByClassName`
3. `getElementsByName` (and its variation `getElementsByName[0]`)

Each test case uses a different method to retrieve elements with the specified ID, class, or name.

**Options Compared**

The options being compared are:

* `getElementById`: Uses the `document.getElementById()` method to retrieve an element by its ID.
* `getElementsByClassName`: Uses the `document.getElementsByClassName()` method to retrieve all elements with a specific class.
* `getElementsByName`: A custom or proprietary method (not standard in JavaScript) that presumably retrieves elements by name.

**Pros and Cons**

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

1. `getElementById`:
	* Pros: Fast, efficient, and widely supported.
	* Cons: May not be suitable for dynamic content or complex DOM structures.
2. `getElementsByClassName`:
	* Pros: Can handle multiple classes and is more flexible than `getElementById`.
	* Cons: May return a long list of elements if there are many matching elements in the DOM, which can impact performance.
3. `getElementsByName` (and its variation):
	* Pros: Not specified, as it's not a standard method in JavaScript.
	* Cons: Likely to be slower and less reliable than the other two methods.

**Other Considerations**

The benchmark also includes metadata about the execution environment, such as:

* Browser: Firefox Mobile 126
* Device Platform: Android
* Operating System: Android

This information helps provide context for the results of each test case.

**Alternatives**

If you're interested in exploring alternative approaches or methods to retrieve elements from an HTML document, here are a few options:

1. `querySelector` and `querySelectorAll`: These methods are part of the DOM API and can be used to select elements based on CSS selectors.
2. `getElementsByTagName`: This method retrieves all elements with a specific tag name.
3. Using query selectors (e.g., `document.querySelector('#foo')`) instead of ID-based retrieval.

These alternatives might offer better performance or flexibility in certain scenarios, but they may also introduce additional complexity or overhead.

Related benchmarks:

getElementById vs getElementsByClassName vs getElementsByName2 (version: 1)

Comparing performance of: getElementById vs getElementsByClassName vs getElementsByClassName[0] vs getElementsByName vs getElementsByName[0]

Created: 2 years ago by: Registered User

Jump to the latest result

getElementById

getElementsByClassName

getElementsByClassName[0]

getElementsByName

getElementsByName[0]

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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