Benchmark: getBoundingClientRect vs offsetLeft

HTML Preparation code:

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

Tests:

getBoundingClientRect
let element = document.getElementById('test'); let rect = element.getBoundingClientRect(); let left = rect.left;
offsetLeft
let element = document.getElementById('test'); let left = element.offsetLeft

Historical Performance Data aggregated from 6 community runs

Desktop Results:

Chrome 6 runs

getBoundingClientRect

1.4M/s

offsetLeft

1.2M/s

Fastest: getBoundingClientRect (1.2x faster)

View exact numbers

✓ getBoundingClientRect : 1,446,498 ops/sec
• offsetLeft: 1,164,197 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
getBoundingClientRect
offsetLeft

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/137.0.0.0 Safari/537.36

Browser/OS: Chrome 137 on Mac OS X 10.15.7

View result in a separate tab

getBoundingClientRect

2.5M/s

offsetLeft

2.2M/s

View exact numbers

Test name	Executions per second
✓ getBoundingClientRect	2,453,267 Ops/sec
offsetLeft	2,176,614 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.

**Benchmark Definition**

The benchmark is defined by a JSON object with three properties:

1. `Name`: The name of the benchmark, which is "getBoundingClientRect vs offsetLeft".
2. `Description`: An empty string, indicating that there is no description for this benchmark.
3. `Script Preparation Code` and `Html Preparation Code`: Both are empty strings, suggesting that no specific code needs to be run before running the benchmark.

**Test Cases**

The benchmark consists of two test cases:

1. `getBoundingClientRect`
2. `offsetLeft`

Both test cases measure the execution time of a JavaScript statement that accesses the `left` property of an element's bounding rectangle using either `getBoundingClientRect()` or `offsetLeft`.

**Options Compared**

Here, we have two options being compared:

Option 1: Using `getBoundingClientRect()`
Option 2: Using `offsetLeft`

**Pros and Cons**

* **Using `getBoundingClientRect()`**:
	+ Pros:
		- Returns a more comprehensive representation of an element's size and position (including top, right, bottom, and width).
		- May be more suitable for complex layouts or elements with non-standard dimensions.
	+ Cons:
		- May introduce unnecessary overhead due to the method requiring multiple lookups and calculations.
* **Using `offsetLeft`**:
	+ Pros:
		- Generally faster, as it only returns the left offset of an element's bounding rectangle.
		- Often sufficient for simple cases where only the horizontal position is needed.
	+ Cons:
		- May not provide a complete picture of an element's size and position (missing top, right, bottom, and width).

**Library and Purpose**

Neither `getBoundingClientRect()` nor `offsetLeft` uses any additional libraries. These are built-in JavaScript methods for accessing element properties.

**Special JS Features/Syntax**

There are no special JavaScript features or syntax used in these test cases. They only rely on standard JavaScript methods and operators.

**Other Alternatives**

If you need to measure the execution time of other element-related properties or methods, consider using `getComputedStyle()`, `clientWidth`, `clientHeight`, `scrollWidth`, `scrollHeight`, or other elements-specific properties.

In conclusion, this benchmark is designed to compare the performance of two commonly used JavaScript methods for accessing an element's left offset: `getBoundingClientRect()` and `offsetLeft`. The results can help developers understand which method is more efficient in their specific use cases.

getBoundingClientRect vs offsetLeft (version: 0)

Comparing performance of: `getBoundingClientRect vs offsetLeft`

Created: 2 years ago by: Guest

Go to the latest result

getBoundingClientRect

offsetLeft

Historical Performance Data aggregated from 6 community runs

Desktop Results:

Chrome 6 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

getBoundingClientRect vs offsetLeft (version: 0)

Comparing performance of: getBoundingClientRect vs offsetLeft

Created: 2 years ago by: Guest

Go to the latest result

getBoundingClientRect

offsetLeft

Historical Performance Data aggregated from 6 community runs

Desktop Results:

Chrome 6 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

Comparing performance of: `getBoundingClientRect vs offsetLeft`