Benchmark: Test samples - MeasureThat.net

Script Preparation code:

var domEl = document.createElement("span"), cls = " aaaaaaaaaaaaaaaaaaaaaa  bbbbbbbbbbbbbbbbb ", _hasCls = function(domEl, cls) {
			var found	= false,
				pos		= domEl.className.indexOf(cls);

			if (pos >= 0) {
				var endpos = pos + cls.length;
				found = endpos == domEl.className.length || domEl.className.charAt(endpos) == ' ';
			}

			return found;
		};

Tests:

Old method
if (!_hasCls(domEl, cls)) { if (domEl.className.length > 0) { cls = ' ' + cls; } domEl.className += cls; }
New trim
cls.trim().split(' ').forEach(function(onecls) { if (onecls) domEl.classList.add(onecls); });
New replace
cls.replace(/\s+/g, ' ').trim().split(' ').forEach(function(onecls) { domEl.classList.add(onecls); });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Old method
New trim
New replace

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 8 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.143 Safari/537.36

Browser/OS: Chrome 53 on Mac OS X 10.11.5

View result in a separate tab

Test name	Executions per second
Old method	2813766.2 Ops/sec
New trim	707339.2 Ops/sec
New replace	545199.9 Ops/sec

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

LLMs can make mistakes. Check important info.

Measuring JavaScript performance is crucial for optimizing applications' execution speed and responsiveness.

The provided JSON represents a benchmark test case on MeasureThat.net, where users can create and run JavaScript microbenchmarks to compare the performance of different approaches.

**Benchmark Definition**

The benchmark definition in the JSON includes three script preparation codes:

1. `Old method`: This approach tests if an element already has the specified class by checking its `className` property using the `_hasCls` function.
2. `New trim`: This approach uses the `trim()` method to remove whitespace from the class name before adding it to the element's `className` property.
3. `New replace`: This approach uses a regular expression to replace one or more whitespace characters with a single space in the class name, and then trims the resulting string using `trim()` before adding it to the element's `className` property.

**Options Compared**

The three script preparation codes are compared to determine which approach is faster. The benchmark results show that:

* `New trim` outperforms both `Old method` and `New replace`.
* `New replace` is slower than both `Old method` and `New trim`.

**Pros and Cons of Different Approaches**

1. **Old method**: This approach is simple and easy to understand, but it may be slower because it involves searching for the class name in the element's `className` property.
2. **New trim**: This approach uses the `trim()` method to remove whitespace from the class name, which can improve performance by reducing the number of characters being searched. However, it may not work correctly if the class name contains special characters or non-printable characters.
3. **New replace**: This approach uses a regular expression to replace one or more whitespace characters with a single space in the class name, which can be slower than using `trim()` because it involves compiling and executing a regular expression.

**Library Used**

None of the script preparation codes use any external libraries.

**Special JavaScript Feature/Syntax**

The `_hasCls` function uses a shorthand syntax to define an anonymous function. The `for...of` loop is used in the `New trim` approach, which is a modern JavaScript feature introduced in ECMAScript 2015 (ES6). The regular expression `/\\s+/g` is used in the `New replace` approach, which is a part of the JavaScript regular expression syntax.

**Other Alternatives**

Other approaches to adding class names to an element's `className` property might include:

* Using the `classList.add()` method, which is supported by most modern browsers and is generally faster than using `innerHTML += ' ' + cls`.
* Using a library like jQuery, which provides a more convenient API for working with CSS classes.
* Optimizing the DOM manipulation code to reduce the number of mutations made to the element's `className` property.

However, these alternatives may not be as simple or straightforward as the three script preparation codes provided in the benchmark definition.

Related benchmarks:

Test samples (version: 0)

Test

Comparing performance of: Old method vs New trim vs New replace

Created: 8 years ago by: Guest

Jump to the latest result

Old method

New trim

New replace

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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