Benchmark: Check if an element contains a class name using a regular expression (v3)

HTML Preparation code:


<div class='hello_world one two three four five six seven eight nine testClass' id='demoBlock'></div>

Script Preparation code:

var el = document.getElementById('demoBlock');

Tests:

loop
for (var i=0, l=el.classList.length; i<l; ++i) { if(/hello_[^\s]+/.test(el.classList[i])) { console.log('found') break; } }
className test
if (/hello_[^\s]+/.test(el.className)) { console.log('found') }
className match
if (el.className.match(/hello_[^\s]+/)) { console.log('found') }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
loop
className test
className match

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 world of JavaScript microbenchmarks.

**What is being tested?**

The provided JSON represents a benchmark test case that measures how efficiently a web browser can check if an HTML element contains a specific class name using different approaches.

In this specific test, the class name being searched for is "testClass". The test creates an HTML element with this class and then checks if it exists in the element's `classList` property or by directly checking the `className` property of the element.

**Options compared**

Three options are being compared:

1. **Looping through `classList`**: This approach uses a loop to iterate over each class name in the `classList` property and checks if any of them match the target class name using a regular expression.
2. **Directly checking `className`**: This approach directly checks if the `className` property contains the target class name using a regular expression.
3. **Using `match()` method**: This approach uses the `match()` method to search for the target class name within the `className` property.

**Pros and Cons**

Here's a brief analysis of each approach:

* **Looping through `classList`**:
	+ Pros: Can be more efficient if there are many classes, as it avoids using regular expressions.
	+ Cons: May be slower than direct checking for small class names, as it involves looping over the array.
* **Directly checking `className`**:
	+ Pros: Simple and fast, as it only involves a single regex operation.
	+ Cons: Can be slower if the class name is very long or contains many special characters, as it requires more processing power to compile the regex.
* **Using `match()` method**:
	+ Pros: Fast and efficient, as it uses optimized regex engines under the hood.
	+ Cons: May not be as straightforward to read and understand, especially for those without extensive experience with regex.

**Library and purpose**

In this test case, no specific library is used. However, it's worth noting that `classList` and `className` properties are part of the HTML5 API, which provides a more modern and efficient way of working with class names in web development.

**Special JS features or syntax**

None mentioned in this specific benchmark.

**Other alternatives**

If you're interested in exploring alternative approaches to this benchmark, here are some other options:

* Using `querySelector` method to search for an element by class name
* Using a more complex regex pattern that captures the entire class name, including any special characters or punctuation
* Comparing different JavaScript engines (e.g., V8, SpiderMonkey) and browsers (e.g., Chrome, Firefox) to see how they perform on this benchmark

Keep in mind that these alternatives might require modifications to the test case code and may not be directly comparable to the original approach.

Related benchmarks:

Check if an element contains a class name using a regular expression (v3) (version: 0)

Comparing performance of: loop vs className test vs className match

Created: 3 years ago by: Guest

Jump to the latest result

loop

className test

className match

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):