Benchmark: class add/remove

HTML Preparation code:

<div class='lazyload'></div>

Script Preparation code:

var e = document.querySelector(".lazyload");

Tests:

Case 1
if (e.className === "lazyload") { e.classList.remove("lazyload"); e.classList.add("lazyloading"); }
Case 2
if (e.className === "lazyload") { e.className = e.className.replace( "lazyload", "lazyloading" ); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Case 1
Case 2

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.83 Safari/537.36 Edg/85.0.564.41

Browser/OS: Chrome 85 on Windows

View result in a separate tab

Test name	Executions per second
Case 1	10215353.0 Ops/sec
Case 2	10285225.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the benchmark and explain what's being tested, compared, and their pros/cons.

**Benchmark Overview**

The benchmark tests two different approaches to remove the `lazyload` class from an HTML element and replace it with `lazyloading`. The test cases are represented by the JSON data provided.

**Script Preparation Code**

The script preparation code is:
```javascript
var e = document.querySelector(".lazyload");
```
This line of code selects an HTML element with the class `lazyload` using the `document.querySelector()` method. This line is executed before each test case.

**Html Preparation Code**

The html preparation code is:
```html
<div class='lazyload'></div>
```
This line of code creates a new HTML element with the class `lazyload`. This element will be modified by the test cases.

**Test Cases**

There are two test cases:

### Case 1

```javascript
if (e.className === "lazyload") {
  e.classList.remove("lazyload");
  e.classList.add("lazyloading");
}
```
This test case uses a direct property access to check if the `className` property of the element is equal to `"lazyload"`. If true, it removes the `lazyload` class and adds the `lazyloading` class.

### Case 2

```javascript
if (e.className === "lazyload") {
  e.className = e.className.replace("lazyload", "lazyloading");
}
```
This test case uses a regular expression to replace `"lazyload"` with `"lazyloading"` in the `className` property of the element. If the element's class name starts with `"lazyload"`, it will be replaced with `"lazyloading"`.

**Comparison**

The two test cases are compared to see which approach is faster. The benchmark measures the number of executions per second for each test case.

**Pros and Cons:**

### Direct Property Access (Case 1)

Pros:

* Simple and efficient
* Fast lookup time

Cons:

* May not work correctly if `className` property is empty or contains only whitespace
* May not be compatible with older browsers that don't support class names as properties

### Regular Expression Replacement (Case 2)

Pros:

* Works correctly even if `className` property is empty or contains only whitespace
* Compatible with older browsers that don't support class names as properties

Cons:

* Slower than direct property access due to regular expression processing time
* May be less efficient for large class names

**Other Considerations**

* The benchmark doesn't consider the security implications of modifying the `className` property. In some cases, this might lead to unexpected behavior or even vulnerabilities.
* The benchmark doesn't account for potential side effects of removing and adding classes, such as changes to the element's styles or layout.

**Library/Functionality Used**

The test cases use the following JavaScript functionality:

* `document.querySelector()` (a method of the `Document` object)
* `e.classList.remove()`
* `e.classList.add()`
* Regular expression replacement (`replace()` method)

These functions are part of the standard JavaScript API and don't require any external libraries.

**Special JS Feature/Syntax**

This benchmark doesn't use any special JavaScript features or syntax. However, it does rely on modern browser support for classes as properties (introduced in ECMAScript 2015).

**Alternatives**

If you want to test alternative approaches, you could consider the following:

* Using a library like Lodash to implement class manipulation functions
* Using a templating engine like Handlebars or Mustache to generate HTML elements with classes
* Using a CSS preprocessor like Sass or Less to define classes and styles
* Using a JavaScript framework like React or Angular to manage class state and updates

Related benchmarks:

class add/remove (version: 0)

Comparing performance of: Case 1 vs Case 2

Created: 4 years ago by: Guest

Jump to the latest result

Case 1

Case 2

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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