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

What is being tested?

The provided benchmark tests two ways to create an array in JavaScript: using the Array() constructor with a length, and using the push() method.

Options being compared

There are two options being compared:

1. new Array(10): This approach creates a new array instance with a fixed length of 10 elements.
2. [] (empty array) + push(): This approach creates an empty array and then uses the push() method to add elements one by one.

Pros and Cons of each approach

1. new Array(10):
   • Pros: Efficient use of memory, as only a single allocation is needed.
   • Cons: May lead to slower startup times if the browser needs to allocate more memory later in the program.
2. [] (empty array) + push():
   • Pros: More flexible and dynamic, allowing for arrays with varying lengths at runtime.
   • Cons: Requires multiple allocations and garbage collections, which can be slower.

Library usage

There is no explicit library mentioned in the benchmark definition or test cases. However, it's worth noting that modern JavaScript engines often use internal libraries to optimize array creation and manipulation.

Special JS feature or syntax

The push() method uses a special property called length to store the number of elements added to the array. This property is not explicitly mentioned in the benchmark definition, but it's an important aspect of how arrays work in JavaScript.

Other alternatives

In addition to these two approaches, there are other ways to create arrays in JavaScript, such as:

1. Array.from(): A more modern method for creating arrays from iterables.
2. Array.of(): Similar to Array.from(), but with a simpler syntax.
3. new Int8Array(10), new Uint8Array(10), etc.: These methods create typed arrays, which are specialized arrays optimized for specific data types.

It's worth noting that these alternatives might not be relevant to the specific benchmark being measured, and may require additional context or setup in order to be useful.