Benchmark Overview

MeasureThat.net is a website that allows users to create and run JavaScript microbenchmarks, including the provided benchmark: "Array.prototype.concat vs spread operator - with Arrays of Objects" (Updated Oct 2020).

Tested Options

The benchmark compares three different approaches for concatenating two arrays in JavaScript:

1. Array.prototype.concat(): The traditional method using the concat() method.
2. Spread Operator at Head (...params): Using the spread operator to add elements to the beginning of the array.
3. Spread Operator at Tail (...params): Using the spread operator to add elements to the end of the array.

Pros and Cons of Each Approach

1. Array.prototype.concat():
   • Pros:
     • Most widely supported and well-documented method.
     • Can be used with arrays of any type, not just objects.
   • Cons:
     • Less efficient than spread operators in modern browsers.
2. Spread Operator at Head (...params):
   • Pros:
     • Can be faster than concat() when the spread operator is implemented efficiently by the browser engine.
   • Cons:
     • Less widely supported and less well-documented than concat().
3. Spread Operator at Tail (...params):
   • Pros:
     • Also can be faster than concat() under similar circumstances as spread at head.
   • Cons:
     • Similar to spread at head, less widely supported and less well-documented.

Libraries Used

None of the benchmark definitions explicitly use any external libraries. However, it's worth noting that modern browsers have built-in support for the spread operator, which was introduced in ECMAScript 2018 (ES2018).

Special JavaScript Features/Syntax

• The spread operator (...), introduced in ECMAScript 2015 (ES2015), allows elements to be added to an array or object without using concat() or other methods.
• Modern browsers, including Chrome Mobile iOS 102, have implemented the spread operator efficiently, making it a viable alternative to concat().

Other Alternatives

In addition to the three approaches tested in this benchmark:

1. Array.prototype.push(): Adding elements to the end of an array using push().
2. Array.prototype.unshift(): Adding elements to the beginning of an array using unshift().
3. Other library functions, such as Lodash's concat() or Immutable.js's concat(), may also be used for concatenating arrays.

Keep in mind that these alternatives are not part of the standard JavaScript API and may have different performance characteristics compared to the tested options.