Let's dive into the provided benchmark.

What is being tested?

MeasureThat.net is testing the performance of two different approaches to select elements based on their data-src attribute:

1. Querying by plain data attribute: This approach uses document.getElementById('wrap').querySelector('[data-src]');. It directly selects an element by its class name, but then filters it based on a specific attribute.
2. Querying by HTML attribute: This approach uses document.getElementById('wrap').querySelector('div[data-src]');. It selects elements based on their HTML data-src attribute.

Options being compared

Two options are being compared:

• Approach 1: Querying by plain data attribute
• Approach 2: Querying by HTML attribute

Pros and Cons of each approach

• Querying by plain data attribute (Approach 1):
  • Pros:
    • Efficient, as it only selects elements based on their class name.
    • Can be faster for complex queries.
  • Cons:
    • Requires an additional filter step, which might lead to slightly slower execution times.
• Querying by HTML attribute (Approach 2):
  • Pros:
    • More concise and readable, as it directly selects elements based on their data-src attribute.
    • Might be faster for simple queries.
  • Cons:
    • Less efficient than Approach 1, as it requires more DOM nodes to be traversed.

Library and syntax used

In the provided benchmark, the querySelector function is used. This function is part of the Document Object Model (DOM) API in JavaScript, which provides a way to select elements based on various criteria.

No additional libraries are required for this benchmark.

Special JS feature or syntax

There is no special JavaScript feature or syntax used in this benchmark. The querySelector function is a standard part of the DOM API and does not rely on any specific browser-specific features or syntax.

Other alternatives

If you were to implement these benchmarks from scratch, here are some alternative approaches:

• Using getElementsByAttribute(): Instead of using querySelector, you could use getElementsByAttribute() to select elements based on their data-src attribute.
• Using a library like jQuery: If you prefer a more concise and readable approach, you could use a library like jQuery to select elements based on their data-src attribute.
• Using a CSS selector: You could also use a CSS selector, such as [data-src], to select elements based on their data-src attribute.

However, these alternatives might introduce additional overhead or dependencies that are not relevant to this benchmark.