Benchmark: getElementById, querySelector, window

HTML Preparation code:

<div id="test">Test</div>

Tests:

getElementById
document.getElementById("test");
querySelector
document.querySelector("#test")
window
window["test"]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
getElementById
querySelector
window

Fastest: N/A

Slowest: N/A

Latest run results:

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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 MeasureThat.net, where JavaScript microbenchmarks come to life!

The provided JSON represents a benchmarking test suite that compares three different ways to access an HTML element: `document.getElementById()`, `document.querySelector()`, and accessing the `window` object directly (`window["test"]`). Let's break down each option:

**1. `document.getElementById()`**

This method retrieves an HTML element by its ID. The syntax `document.getElementById("test")` is used to access the `<div>` element with the ID "test".

Pros:

* Widely supported across browsers and platforms.
* Easy to use, as it's a straightforward method.

Cons:

* May be slower than other methods due to the need to traverse the DOM tree.

**2. `document.querySelector()`**

This method retrieves an HTML element by its CSS selector. The syntax `document.querySelector("#test")` is used to access the `<div>` element with the ID "test".

Pros:

* Can be faster than `getElementById` for more complex selectors.
* Supports more advanced selector patterns.

Cons:

* May not work as expected in older browsers or those with limited CSS support.
* Can be slower due to the need to parse and execute the CSS selector.

**3. `window["test"]`**

This method accesses a property directly on the `window` object using bracket notation (`window["test"]`). In this case, it's used to access the value of the "test" property (the `<div>` element).

Pros:

* Can be faster due to the direct access.
* Works in most browsers and platforms.

Cons:

* Limited support: only works for accessing properties on the `window` object, not other objects or properties.
* May require careful handling of cases where the property is `undefined` or `null`.

The MeasureThat.net benchmarking framework uses these three options to compare their performance. The results show that Firefox 101 performs relatively well across all three methods.

**Library and Special JS Features**

None of the test cases rely on any external libraries, special JavaScript features, or syntax beyond basic ECMAScript.

**Other Alternatives**

If you were to implement similar benchmarking tests for other methods, here are some additional options to consider:

* `document.querySelectorAll()`: retrieves all elements that match a CSS selector.
* `Element.prototype.contains()`: checks if an element contains another element.
* Using `requestIdleCallback()` or `setImmediate()` to schedule tasks and measure their performance.

Keep in mind that each of these alternatives has its own pros and cons, and may not be as widely supported or performant as the original three options.

Related benchmarks:

getElementById, querySelector, window (version: 0)

Comparing performance of: getElementById vs querySelector vs window

Created: 8 years ago by: Guest

Jump to the latest result

getElementById

querySelector

window

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):