Let's break down the benchmark and its test cases.

What is being tested?

The provided JSON represents two microbenchmarks that compare the performance of two approaches: using the includes method and using the indexOf method to filter an array in JavaScript. The benchmarks are designed to measure the execution speed of these methods on a list of 1000 objects, where some items are already present in the list.

Options compared

The two test cases compare the performance of:

1. Includes method: This method checks if a specific item is present in an array using the includes function.
2. IndexOf method: This method returns the index of a specific item in an array, and then uses this index to determine if the item is present (if it's -1, the item is not present).

Pros and Cons

• Includes method:
  • Pros: Simple, efficient, and widely supported.
  • Cons: Can be slower than indexOf for large arrays because it requires iterating over the array until a match is found.
• IndexOf method:
  • Pros: Can be faster than includes for large arrays because it returns an index immediately, reducing iteration time. Also, it's often more efficient for exact matches.
  • Cons: Requires a separate step to determine if the returned index is -1, which can add overhead.

Other considerations:

• The benchmarks are run on a Linux desktop with Chrome 76 browser, so the results might not be representative of other platforms or browsers.
• The list size (1000) and item count (2 new items) are relatively small, which might affect the performance difference between includes and indexOf.
• Both methods have a time complexity of O(n), where n is the array length. However, in practice, modern JavaScript engines often optimize these functions to be faster.

Library and syntax

Neither test case uses any external libraries or special JS features beyond standard JavaScript functionality.

Benchmark preparation code

The script preparation code creates an array list with 1000 objects, each representing a product, and adds two new items (newItems) that are not present in the list. The newItemIds variable is created by mapping the id property of newItems to an array.

Benchmark execution

The benchmark is executed multiple times (not specified), and the results are collected for each test case. The latest available result shows:

• For the includes method, Chrome 76 on Linux desktop executes approximately 4827 executions per second.
• For the indexOf method, Chrome 76 on Linux desktop executes approximately 4397 executions per second.

Alternatives

Other alternatives to these methods might include:

• Using a Set data structure to keep track of present items, which can be faster for large arrays.
• Implementing a custom filtering function using bitwise operations or other optimization techniques.
• Using a different programming language or framework that provides more efficient array searching functionality.