Benchmark Overview

The benchmark compares two different methods of adding elements to an array in JavaScript: using the push() method with the spread operator (...) and using a for-of loop with push(). The benchmark aims to measure which of these two approaches performs better in terms of execution speed.

Test Cases

1. Push:

   • Code: const arr1 = []\r\narr1.push(...arr)
   • Description: This method utilizes the spread operator to expand the contents of the array arr when adding them to arr1. The spread operator allows the elements of arr to be 'spread' into push(), enabling all elements to be pushed at once.

2. Spread:

   • Code: const arr1 = []\r\nfor (const element of arr){\r\n arr1.push(element)\r\n}\r\n
   • Description: This method iterates over each element in arr and individually pushes each element to arr1. It uses a standard for-of loop to traverse the array and applies the push() method sequentially for each item.

Pros and Cons

Using Spread (push(...arr)):

• Pros:

  • More concise and expressive, making the code cleaner and easier to read.
  • Tends to be faster for bulk operations since it can handle the entire array in one function call.

• Cons:

  • Uses more memory because the spread operator creates a shallow copy or expands the elements at the moment of pushing. For very large arrays, this could lead to performance overhead.
  • Not all environments may support the spread operator, although it's widely supported in modern JavaScript.

Using For-Of Loop:

• Pros:

  • Provides fine-grained control over each element being processed during the push operation.
  • More memory-efficient for very large arrays since it pushes elements directly without creating intermediate copies.

• Cons:

  • More verbose, leading to potentially harder-to-read code compared to the spread operator.
  • May execute slower because it involves multiple function calls to push() for each element in the array.

Benchmark Results

• Test Name: Push:
  • Executions Per Second: 118,939.85
• Test Name: Spread:
  • Executions Per Second: 64,547.91

From the results, it is evident that the use of the spread operator (push(...arr)) significantly outperforms the for-of loop method in this specific case, with nearly double the executions per second.

Other Considerations

• Environment: The results can vary depending on the JavaScript engine (for example, V8 in Chrome, SpiderMonkey in Firefox) and the environment (desktop vs. mobile). In some cases, advanced optimizations might be applied differently in these engines.
• Array Size: For very small arrays, the difference in performance between the two methods may be negligible. However, as the size of the array grows, the disparity in performance becomes more noticeable.
• Code Maintainability: The choice between the two methods should also consider code readability and maintainability, particularly for larger codebases where team members may have varying levels of experience.

Alternatives

Other than the methods tested, array concatenation can be performed using Array.prototype.concat() or leveraging functional approaches such as map() or reduce(), though they are generally less performant for this use case. Each alternative comes with its own trade-offs in terms of readability, performance, and memory utilization, which should be carefully weighed against the specific requirements of the project at hand.