Benchmark: Cached querySelector

HTML Preparation code:

<div id="fir" class="hi">
  <div id='no' class="ss">
  	<div id='ff' class="fox">
      <button class="target"></button>
      <button class="target"></button>
      <button class="target"></button>
    </div>
  </div>
</div>

Script Preparation code:

var cache = {};

Tests:

uncached
var el = document.querySelectorAll('target');
cached
var el = cache['target']; if (!el) { el = document.querySelectorAll('target'); cache['target'] = el; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
uncached
cached

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:146.0) Gecko/20100101 Firefox/146.0

Browser/OS: Firefox 146 on Linux

View result in a separate tab

Test name	Executions per second
uncached	2940788.5 Ops/sec
cached	948609024.0 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmark Overview**

The benchmark is designed to test whether caching the `querySelector` method makes a difference in the execution time of the code. The benchmark creates two test cases:

1. **Uncached**: This test case runs `document.querySelectorAll('target')` without any caching.
2. **Cached**: This test case uses a cache object (`var cache = {};`) to store the results of previous executions. If the result is not found in the cache, it executes `document.querySelectorAll('target')` and stores the result in the cache.

**Comparison of Approaches**

The two approaches being compared are:

1. **Uncached**: This approach runs `document.querySelectorAll('target')` on every execution, without any caching. The browser has to re-compute the query selector for each execution.
2. **Cached**: This approach uses a cache object to store the results of previous executions. If the result is not found in the cache, it executes `document.querySelectorAll('target')` and stores the result in the cache.

**Pros and Cons**

* **Uncached**:
	+ Pros: Simple, easy to understand, and doesn't require additional memory.
	+ Cons: Every execution requires a full re-computation of the query selector, which can be time-consuming.
* **Cached**:
	+ Pros: Can reduce the execution time by reusing previously computed results. Also, it allows for more control over caching.
	+ Cons: Requires an additional data structure (the cache object) to store and manage the cached results.

**Library and Purpose**

In this benchmark, the `querySelector` method is a part of the JavaScript DOM API. It's used to select all elements with a given tag name or CSS selector.

The cache library (or rather, the simple cache object created in the script preparation code) is not a separate library, but rather a custom implementation for caching results. This approach allows the benchmark to test whether caching makes a difference without relying on an external library.

**Special JS Feature or Syntax**

There doesn't appear to be any special JavaScript features or syntax being used in this benchmark. The focus is on testing the caching behavior of the `querySelector` method.

**Other Alternatives**

If you were to implement this benchmark using a different approach, some alternatives could include:

1. **Use a more robust caching library**: Instead of creating a simple cache object, you could use a more robust library like LRU Cache or Redis to store and manage cached results.
2. **Use a different query selector method**: Some browsers support alternative query selector methods, such as `querySelectorAll` with a `deep` option or using the `querySelector` method in combination with `textContent`.
3. **Test caching behavior at runtime**: Instead of testing caching behavior by executing multiple runs with caching enabled/disabled, you could test it at runtime using tools like Chrome DevTools or Node.js Inspector.

Keep in mind that the specific alternatives will depend on the requirements and goals of your benchmark.

Related benchmarks:

Cached querySelector (version: 0)

Testing if caching querySelector makes a diference

Comparing performance of: uncached vs cached

Created: 5 years ago by: Guest

Jump to the latest result

uncached

cached

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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