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

Benchmark Definition and Purpose

The provided JSON represents a benchmark that compares two approaches for concatenating arrays: the traditional concat() method and the new ES6 spread operator (...). The purpose of this benchmark is to determine which approach is faster in JavaScript.

Options Compared

There are two test cases:

1. Spread Operator ([ ...array1, ...array2 ]): This option uses the spread operator to concatenate array1 and array2. It's a concise way to create a new array by copying elements from an existing array.
2. Concat into Empty Array (var final = array1.concat(array2)): This option concatenates array1 and array2 using the concat() method, which creates a new array by copying elements from each input array.

Pros and Cons

• Spread Operator: Pros:
  • Concise and expressive syntax.
  • Creates a new array without modifying the original arrays. Cons:
  • Can be slower in older browsers or with large inputs due to the overhead of creating a new array.
• Concat into Empty Array: Pros:
  • Often faster than the spread operator, especially for small inputs, since it avoids creating a new array.
  • Wide browser support, including older versions. Cons:
  • Less concise syntax, which can make code harder to read.

Library and Purpose (None in this case)

There are no external libraries used in this benchmark. The tests rely solely on built-in JavaScript features.

Special JS Feature or Syntax (Spread Operator)

The spread operator ([ ...array1, ...array2 ]) is a new feature introduced in ECMAScript 2015 (ES6). It allows you to create a new array by copying elements from an existing array. This syntax was not available in older versions of JavaScript.

Other Alternatives

If you need to concatenate arrays, there are other approaches:

• Using Array.prototype.push(): array1.push(...array2);
• Creating a new array using the Array.from() method: Array.from(array1).concat(Array.from(array2))

Keep in mind that these alternatives may have different performance characteristics compared to the spread operator and the concat() method.

I hope this explanation helps you understand the benchmark and its options!