Benchmark: getElementById vs HTML5 global variable based on id value fixed

HTML Preparation code:

<table id="testTable">
</table>

Script Preparation code:

// some elemens without id
for(var i=0; i<5000; ++i)
  testTable.insertRow(-1).insertCell(-1).textContent = 'Row #'+i;

// some elements with id
for(var i=0; i<5000; ++i)
{
  var div = document.createElement('div');
  div.id = 'divBefore'+i;
  testTable.parentElement.insertBefore(div, testTable);
  
  div = document.createElement('div');
  div.id = 'divAfter'+i;
  testTable.parentElement.appendChild(div);
}

Tests:

getElementById each time
for(var i=0; i<10000; ++i) { var table = document.getElementById('testTable'); table.rows[0].cells[0].textContent = 'Test'; }
Own global variable
var table = document.getElementById('testTable'); for(var i=0; i<10000; ++i) { table.rows[0].cells[0].textContent = 'Test'; }
Own global variable with equal name
var testTable = document.getElementById('testTable'); for(var i=0; i<10000; ++i) { testTable.rows[0].cells[0].textContent = 'Test'; }
HTML5 global variable based on id value
for(var i=0; i<10000; ++i) { testTable.rows[0].cells[0].textContent = 'Test'; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
getElementById each time
Own global variable
Own global variable with equal name
HTML5 global variable based on id value

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's dive into the benchmark and explore what's being tested.

**Benchmark Definition**

The benchmark defines four test cases:

1. `getElementById each time`: This test case uses `document.getElementById` to retrieve an element by its ID, performs some operations on it, and then repeats this process 10,000 times.
2. `Own global variable`: Similar to the first test case, but instead of using `document.getElementById`, it assigns the result to a global variable `table`.
3. `Own global variable with equal name`: Same as the second test case, but the global variable has the same name as the element's ID (`testTable`).
4. `HTML5 global variable based on id value`: This test case uses the new HTML5 feature, `named access on the window object`, to retrieve an element by its ID and perform operations on it.

**Options Compared**

The benchmark compares four different approaches:

1. **`document.getElementById`**: A traditional method of retrieving an element by its ID.
2. **Assigning result to a global variable (`table`)**: Stores the result in a global variable, which can lead to caching and performance implications.
3. **Assigning result to a local variable with equal name as the element's ID (`testTable`)**: Similar to the second approach, but with a local variable having the same name as the element's ID.
4. **HTML5 global variable based on id value**: Utilizes the new HTML5 feature to retrieve an element by its ID, which can provide better performance and caching.

**Pros and Cons**

Here are some pros and cons of each approach:

1. **`document.getElementById`**:
	* Pros: Simple and widely supported.
	* Cons: Can lead to slow performance due to DOM lookup.
2. **Assigning result to a global variable (`table`)**:
	* Pros: Can provide caching, reducing the number of DOM lookups.
	* Cons: May not be suitable for all use cases (e.g., when `table` is reassigned).
3. **Assigning result to a local variable with equal name as the element's ID (`testTable`)**:
	* Pros: Similar to the second approach, but with a local variable.
	* Cons: Same limitations as the second approach.
4. **HTML5 global variable based on id value**:
	* Pros: Provides better performance and caching due to named access.
	* Cons: Requires support for HTML5 features.

**Other Considerations**

When using `document.getElementById`, consider the following:

* The document may not exist or be accessible when trying to retrieve an element by its ID.
* The element's ID may change dynamically, affecting the accuracy of the benchmark.

The `named access on the window object` feature (HTML5) is a more efficient way to retrieve elements by their ID. However, it requires careful consideration of compatibility and support for different browsers.

**Alternatives**

Other alternatives for retrieving elements by their ID include:

* Using a library like jQuery or a custom implementation.
* Utilizing a virtual DOM or a lightweight DOM library.
* Employing a caching mechanism, such as memoization or a cache store.

Keep in mind that each alternative has its pros and cons, which should be evaluated on a case-by-case basis.

Related benchmarks:

getElementById vs HTML5 global variable based on id value fixed (version: 0)

https://html.spec.whatwg.org/#named-access-on-the-window-object

Comparing performance of: getElementById each time vs Own global variable vs Own global variable with equal name vs HTML5 global variable based on id value

Created: 3 years ago by: Guest

Jump to the latest result

getElementById each time

Own global variable

Own global variable with equal name

HTML5 global variable based on id value

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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