Overview

MeasureThat.net is a web-based platform for creating and running JavaScript microbenchmarks. The provided benchmark tests the performance of three methods to retrieve the width of an HTML element: clientWidth, offsetWidth, and window.getComputedStyle. We'll dive into each test case, discuss the pros and cons of different approaches, and explore any notable libraries or features used in the benchmark.

Test Cases

The benchmark consists of three individual test cases:

1. clientWidth

document.getElementById('teste').clientWidth;

This test case measures the performance of retrieving the client width of an HTML element using the clientWidth property.

2. offsetWidth

document.getElementById('teste').offsetwidth;

This test case measures the performance of retrieving the offset width of an HTML element using the offsetWidth property.

3. window.getComputedStyle

parseFloat(window.getComputedStyle(document.getElementById('teste')).width);

This test case measures the performance of retrieving the width of an HTML element using the getComputedStyle method and parsing its value as a float.

Options Compared

The three test cases compare the following options:

• clientWidth: Retrieves the client width of an HTML element, which includes only the content's own width.
• offsetWidth: Retrieves the offset width of an HTML element, which includes the content's own width and any additional padding, border, or margin applied to the element.
• window.getComputedStyle: Retrieves the computed style of an HTML element, which returns a CSSOMStyle object that can be used to access various style properties.

Pros and Cons

Here are some pros and cons for each approach:

• clientWidth:
  • Pros: Simple and efficient, as it only requires accessing a single property.
  • Cons: May not account for additional styling applied to the element.
• offsetWidth:
  • Pros: Includes the content's own width and any additional padding, border, or margin applied to the element.
  • Cons: More computationally expensive than clientWidth, as it requires accessing multiple properties.
• window.getComputedStyle:
  • Pros: Provides more precise control over styling, as it returns a CSSOMStyle object that can be used to access various style properties.
  • Cons: Requires parsing the parsed value of the width property, which may introduce additional overhead.

Library and Features

None of the test cases use any notable libraries or features beyond JavaScript's built-in DOM APIs. However, window.getComputedStyle relies on the CSSOM (CSS Object Model) API, which is a standard for accessing and manipulating CSS styles in web browsers.

Special JS Feature or Syntax

There are no special JS features or syntax used in this benchmark beyond JavaScript's built-in DOM APIs and CSSOM API.

Other Alternatives

If you're looking for alternatives to these test cases, consider the following:

• For retrieving an element's width without using clientWidth or offsetWidth, you could use getBoundingClientRect() or scrollWidth.
• If you need more precise control over styling, you could use a CSS library like Sass or Less.
• To measure the performance of different styling approaches, consider creating additional test cases for various CSS-related operations.

In conclusion, this benchmark provides a useful comparison of three methods to retrieve an HTML element's width: clientWidth, offsetWidth, and window.getComputedStyle. Understanding the pros and cons of each approach can help developers make informed decisions about their own code.