Let's dive into the world of JavaScript microbenchmarks!

What is tested on MeasureThat.net?

MeasureThat.net tests different approaches to concatenating arrays in JavaScript, specifically comparing Array.concat() and spread syntax (...).

Options compared:

There are two options being compared:

1. Array.concat(): This method takes an array as an argument and returns a new array that contains all elements from the original array.
2. Spread syntax (...): This method uses the ... operator to create a new array by spreading the elements of another array.

Pros and Cons:

• Array.concat():
  • Pros:
    • Wide browser support (all major browsers)
    • Well-documented
  • Cons:
    • Can be slower than spread syntax, especially for large arrays
    • Returns a new array object every time it's called, which can lead to performance issues in certain situations
• Spread syntax (...):
  • Pros:
    • Often faster than Array.concat(), especially for large arrays
    • Creates a new array without the need for explicit method calls
  • Cons:
    • Not supported in older browsers (IE 11 and below)
    • Can be less readable in certain situations

Library usage:

None of the test cases uses any external libraries.

Special JavaScript feature or syntax:

The ... operator is a new feature introduced in ECMAScript 2015, also known as ES6. It allows you to create a new array by spreading elements from another array or iterable.

Other alternatives:

If Array.concat() and spread syntax are not available or performance-critical, other alternatives for concatenating arrays include:

• Using the + operator to concatenate arrays (e.g., [1, 2, 3] + [4, 5, 6])
• Using the Array.prototype.push() method to add elements to an array and then creating a new array from it (e.g., [...new Array(7).fill(null), 1, 2, 3].slice(0, 3))

However, these alternatives are generally less efficient and less readable than using Array.concat() or spread syntax.

Overall, the choice between Array.concat() and spread syntax depends on the specific use case, browser support requirements, and performance considerations.