Benchmark: var vs document.body

HTML Preparation code:

<div class="test"></div>

Tests:

var
var db = document.body; db.querySelectorAll(".test")
document.body
document.body.querySelectorAll(".test")

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
var
document.body

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

**Benchmark Definition**

The provided JSON represents a simple benchmark test between two approaches: using `var` and `document.body`. The benchmark aims to measure which approach is faster for querying DOM elements using `querySelectorAll`.

**Options Compared**

Two options are compared:

1. **Using `var`**: In this approach, a variable named `db` is declared and assigned the value of `document.body`.
2. **Directly using `document.body`**: This approach assigns the `document.body` object directly to the test variable.

**Pros and Cons**

* **Using `var`**:
	+ Pros: The variable can be used as a proxy for `document.body`, which might help with caching or reusing the result.
	+ Cons: It adds an unnecessary step, as it requires declaring and assigning a variable before using `document.body`.
* **Directly using `document.body`**:
	+ Pros: This approach is more concise and directly utilizes the `document.body` object, which reduces overhead.
	+ Cons: The cache-busting effect of reusing `document.body` might be lost.

**Library Usage**

There are no external libraries used in this benchmark. However, it's worth noting that MeasureThat.net uses a library to parse the HTML and JavaScript code, as well as to execute the benchmarks.

**Special JS Feature or Syntax**

There is no special JS feature or syntax being tested here. The focus is solely on comparing two approaches for querying DOM elements.

**Other Alternatives**

While not directly compared in this benchmark, other alternatives could be:

* Using `const` instead of `var`, which would provide a similar benefit to reusing the object reference.
* Using a different approach, such as using `document.querySelector()` or `getElementsByClassName()`, which might have different performance characteristics.

**Benchmark Preparation Code and Individual Test Cases**

The provided JSON includes the benchmark definition, script preparation code, HTML preparation code, and individual test cases. The script preparation code is empty in this case, but it's likely used to initialize variables or perform setup tasks before running the benchmarks. Each test case consists of a single benchmark definition, which specifies the JavaScript code to be executed.

**Latest Benchmark Results**

The provided JSON includes two benchmark results:

* One result for the "document.body" approach with an execution rate of approximately 164,916.84375 executions per second.
* Another result for the "var" approach with an execution rate of approximately 166,210.0625 executions per second.

These results suggest that using `var` might have a slight performance advantage in this particular benchmark. However, it's essential to note that this is just one measurement and may not be representative of all scenarios or environments.

Related benchmarks:

var vs document.body (version: 0)

Comparing performance of: var vs document.body

Created: 8 years ago by: Guest

Jump to the latest result

var

document.body

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):