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

What is being tested?

The benchmark compares two ways to check if an element has a specific attribute or data property: hasAttribute and in dataset. Specifically, it tests whether element.hasAttribute("data-foo") is faster than element["dataset"] == "foo" (or simply "foo" in element.dataset) for the case where the element has a data-foo attribute.

Options compared:

There are two options being compared:

1. hasAttribute: This method checks if an element has a specific attribute by calling the getAttribute() method and checking if the returned value is truthy.
2. in dataset: This method uses the in operator to check if a property exists in the dataset object of an element.

Pros and Cons:

1. hasAttribute:
   • Pros: Simple, lightweight, and widely supported by browsers.
   • Cons: May involve additional overhead due to attribute lookup, as getAttribute() must be called and then checked for truthiness.
2. in dataset:
   • Pros: Can be more efficient than hasAttribute, as it only requires a single property access and does not require an extra call to getAttribute().
   • Cons: May not work in older browsers that do not support the dataset object or its syntax.

Other considerations:

• Library usage: The benchmark uses the element object, which is likely part of the DOM API. In this case, no library is explicitly used.
• Special JS features/syntax: No special JavaScript features or syntax are used in these test cases (e.g., async/await, arrow functions, etc.).

Alternatives:

If you're interested in testing other methods for checking attributes or data properties, you could consider adding new benchmark definitions with the following alternatives:

• Using element.getAttribute("data-foo") === "foo" instead of hasAttribute
• Using Object.prototype.hasOwnProperty.call(element.dataset, "foo") instead of in dataset
• Using a library like Lodash's get() method or a custom implementation for attribute checking

Keep in mind that these alternatives might have different performance characteristics and may require additional setup or modifications to the benchmark.