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

Benchmark Definition and Purpose

The benchmark, "Array concat vs spread operator vs push new", compares three ways to concatenate arrays in JavaScript:

1. concat()
2. The ES6 spread operator (...)
3. push(...) with multiple arguments

The purpose of this benchmark is to determine which method is the most efficient.

Options Compared

We have three options being compared:

1. concat(): A traditional method for concatenating arrays in JavaScript.
2. Spread Operator (...): A new ES6 feature that allows you to spread an array into multiple arguments.
3. push(...) with multiple arguments: A way to push elements onto an array using the spread operator.

Pros and Cons of Each Approach

Here's a brief overview of each approach:

1. concat():
   • Pros: widely supported, easy to use.
   • Cons: creates a new array object, can be slower for large arrays.
2. Spread Operator (...):
   • Pros: efficient, modern way of concatenating arrays.
   • Cons: requires ES6 support, may have unexpected behavior if not used carefully.
3. push(...) with multiple arguments:
   • Pros: efficient, can be faster than concat() for large arrays.
   • Cons: requires multiple arguments (the spread operator), may have unexpected behavior if not used carefully.

Library Used

There is no explicit library mentioned in the benchmark definition or test cases. However, it's likely that the benchmark is running in a browser environment, which uses the V8 JavaScript engine.

Special JS Feature or Syntax

The ES6 spread operator (...) is a special feature introduced in ECMAScript 2015. It allows you to spread an array into multiple arguments, making it more concise and efficient than traditional concatenation methods.

Benchmark Test Cases

Each test case consists of:

1. A benchmark definition: the code snippet that performs the concatenation.
2. A Test Name: a descriptive name for the test case (e.g., "Array.prototype.concat").

The three test cases are:

1. concat(): Concatenates two arrays using the concat() method.
2. Spread Operator (...): Concatenates two arrays using the spread operator.
3. push(...) with multiple arguments: Pushes elements onto an array using the spread operator.

Latest Benchmark Results

The latest benchmark results show the execution speed of each test case in Chrome 83 on a Windows desktop:

1. Push (Spread Operator): 125,528,560 executions per second
2. spread operator: 115,818,270 executions per second
3. Array.prototype.concat: 36,197,995 executions per second

The results suggest that the push(...) with multiple arguments and spread operator methods are faster than the traditional concat() method.

Alternatives

Other alternatives for concatenating arrays in JavaScript include:

• Using Array.prototype.push() and then passing an array of elements: arr.push(...newArr)
• Using a library like Lodash or Ramda
• Using a custom implementation, such as using a single loop to concatenate elements

Keep in mind that these alternatives may have different performance characteristics or use cases compared to the methods being benchmarked.