<html>
<body>
<div>
<div>
<div>
<div class="element">
<div class="test"></div>
</div>
</div>
</div>
</div>
</body>
</html>
window.element = document.querySelector('.element');
const theHtml = document.querySelector('.test');
const theHtml = element.querySelector('.test');
--enable-precise-memory-info
flag.
Test case name | Result |
---|---|
querySelector from document | |
querySelector from element |
Test name | Executions per second |
---|---|
querySelector from document | 3871085.8 Ops/sec |
querySelector from element | 5430846.0 Ops/sec |
Overview of the Benchmark
The provided JSON represents a JavaScript microbenchmark that tests the performance difference between two approaches to use the querySelector
method: calling it directly on the document
object or on an element closer to the target element.
Options Compared
Two options are compared:
document.querySelector('.test')
, where .test
is a CSS selector targeting an element with the class "test".element
, which is set to document.querySelector('.element')
, and then calls element.querySelector('.test')
. The intermediate element is created by selecting an element with the class "element" and assigning it to a variable named "element".Pros and Cons of Each Approach
document
object needs to be traversed, which can lead to slower performance in some cases.element
) adds overhead due to memory allocation and management. Additionally, this approach relies on the specific structure of the HTML document, which may not always match expectations.Library Usage
None of the provided benchmark scripts explicitly uses any external libraries. However, it's worth noting that querySelector
is a part of the DOM API, which is built into modern browsers.
Special JS Features or Syntax
There are no specific JavaScript features or syntax mentioned in the provided benchmark definition. The code adheres to standard ECMAScript syntax and conventions.
Other Alternatives
If you want to explore alternative approaches or optimize your own benchmarks, consider the following options:
querySelectorAll
with a query string).Keep in mind that the specific optimizations will depend on your project's requirements, target audience, and performance constraints.