Overview

MeasureThat.net is a website that allows users to create and run JavaScript microbenchmarks. The benchmark provided measures the performance of three different approaches to divide an array by 2: right shift, divide and floor, and another variant of divide and floor using bitwise truncation (~~).

Benchmark Definition JSON

The benchmark definition JSON contains information about the test case:

• Name: The name of the benchmark, which is "Right shift VS Divide and floor 2".
• Description: An empty string, indicating that no description is provided.
• Script Preparation Code: A script that generates an array of 10,000 random numbers between 0 and 10. This code is executed before each test case to ensure a fresh starting point for the tests.
• Html Preparation Code: An empty string, indicating that no HTML preparation code is required.

Individual Test Cases

The benchmark definition also contains three individual test cases:

1. Right shift: The test case measures the performance of the right shift operator (>>) on the generated array.
2. Divide and floor: The test case measures the performance of dividing an array element by 2 using the / operator and then taking the floor value using Math.floor().
3. Divide and floor 2: The test case measures the performance of another variant of divide and floor, which uses bitwise truncation (~~) to truncate the result to the nearest integer.

Options Compared

The benchmark compares three different approaches:

• Right shift: This approach uses the right shift operator (>>) to divide an array element by 2. This is a simple and efficient operation that relies on the binary representation of the numbers.
• Divide and floor: This approach uses the / operator to divide an array element by 2, followed by Math.floor() to take the floor value. This approach can be slower than right shift due to the overhead of the division operation.
• Divide and floor 2: This approach uses bitwise truncation (~~) to truncate the result of dividing an array element by 2 to the nearest integer. This approach is similar to divide and floor but avoids the overhead of Math.floor().

Pros and Cons

Here's a summary of the pros and cons of each approach:

• Right shift: Pros:
  • Fastest operation due to its simple binary representation-based implementation.
  • Least overhead. Cons:
  • May not be as accurate as other approaches due to potential rounding errors.
• Divide and floor: Pros:
  • Accurate results, as it uses the / operator followed by Math.floor(). Cons:
  • Slower than right shift due to the overhead of division and Math.floor().
• Divide and floor 2: Pros:
  • Similar accuracy to divide and floor but with reduced overhead due to bitwise truncation. Cons:
  • May have rounding errors if not implemented carefully.

Library: Math

The benchmark uses the Math library for the Math.floor() function, which is a standard JavaScript library that provides mathematical functions.

Special JS Feature/Syntax

None of the test cases use any special JavaScript features or syntax that are unique to modern browsers. They rely on basic JavaScript operations and libraries like Math.

Other Alternatives

If you want to explore alternative approaches, here are some options:

• Use a different data structure, such as an array of integers with a fixed size.
• Compare the performance of other division operators, such as the / operator without Math.floor().
• Add more test cases that compare different operations or algorithms.

Keep in mind that the specific benchmark and test cases may not be representative of real-world scenarios, but they can still provide valuable insights into the performance characteristics of different JavaScript approaches.